diff --git a/03_UDP/.gitignore b/03_UDP/.gitignore
new file mode 100644
index 0000000..ba2906d
--- /dev/null
+++ b/03_UDP/.gitignore
@@ -0,0 +1 @@
+main
diff --git a/03_UDP/include/Client.h b/03_UDP/include/Client.h
new file mode 100644
index 0000000..857bc77
--- /dev/null
+++ b/03_UDP/include/Client.h
@@ -0,0 +1,28 @@
+#pragma once
+
+#include <stddef.h>
+#include <cstdint>
+#include <vector>
+#include <string>
+#include "Network.h"
+#include "SimpleChecker.h"
+
+typedef uint64_t calc_t;
+
+class Client
+{
+private:
+    static const calc_t CODE_GET_MAX_SIMPLE = 1;
+    static const calc_t CODE_GET_LAST_N = 2;
+    static const calc_t CODE_CALCULATE = 3;
+    static const calc_t CODE_SEND_CALCULATED = 4;
+
+    Network _network;
+
+public:
+    Client(std::string host_name, uint16_t port);
+
+    calc_t get_max_prime() const;
+    std::vector<calc_t> get_last_n(calc_t n) const;
+    void calculate(calc_t n) const;
+};
\ No newline at end of file
diff --git a/03_UDP/include/Network.h b/03_UDP/include/Network.h
new file mode 100644
index 0000000..be4685b
--- /dev/null
+++ b/03_UDP/include/Network.h
@@ -0,0 +1,51 @@
+#pragma once
+
+#include <stddef.h>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+#include <netdb.h>
+#include <netinet/in.h>
+#include <unistd.h>
+
+#include <cstdint>
+#include <vector>
+#include <string>
+
+struct NetworkException
+{
+private:
+    std::string message;
+
+public:
+    NetworkException(std::string message)
+    : message(message)
+    {
+    }
+
+    std::string get_message() const
+    {
+        return message;
+    }
+};
+
+class Network
+{
+private:
+    static const size_t MAX_LEN = 500;
+    static const size_t TIME_OUT_SEC = 5;
+
+    std::string _host_name;
+    uint16_t _port;
+
+    int try_send_message(char* message, size_t message_length, char* response) const;
+    uint64_t get_check_sum(const std::vector<uint64_t> &v, size_t prefix_length) const;
+    size_t data2message(const std::vector<uint64_t> &message_data, size_t size_num, char* message) const;
+    int massage2data(char* response, int response_length, size_t size_num, std::vector<uint64_t> &response_data) const;
+
+public:
+    Network(std::string host_name, uint16_t port);
+
+    std::vector<uint64_t> send_message(const std::vector<uint64_t> &v, size_t size_num) const;
+};
\ No newline at end of file
diff --git a/03_UDP/include/SimpleChecker.h b/03_UDP/include/SimpleChecker.h
new file mode 100644
index 0000000..4e68242
--- /dev/null
+++ b/03_UDP/include/SimpleChecker.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <stddef.h>
+#include <cstdint>
+#include <vector>
+
+class SimpleChecker
+{
+public:
+    SimpleChecker() = delete;
+
+    static bool is_prime(uint64_t n);
+    static std::vector<uint64_t> check_interval(uint64_t start_num, size_t n);
+};
\ No newline at end of file
diff --git a/03_UDP/src/Client.cpp b/03_UDP/src/Client.cpp
new file mode 100644
index 0000000..b83f9b8
--- /dev/null
+++ b/03_UDP/src/Client.cpp
@@ -0,0 +1,70 @@
+#include "Client.h"
+
+using std::string;
+using std::vector;
+
+Client::Client(string host_name, uint16_t port)
+: _network(host_name, port)
+{
+}
+
+calc_t Client::get_max_prime() const
+{
+    vector<uint64_t> message;
+    message.push_back((uint64_t)CODE_GET_MAX_SIMPLE);
+
+    vector<uint64_t> response;
+    do {
+        response = _network.send_message(message, sizeof(calc_t));
+    } while (response.size() != 1);
+
+    calc_t res = (calc_t)response[0];
+    return res;
+}
+
+vector<calc_t> Client::get_last_n(calc_t n) const
+{
+    vector<uint64_t> message;
+    message.push_back((uint64_t)CODE_GET_LAST_N);
+    message.push_back((uint64_t)n);
+
+    vector<uint64_t> response;
+    do {
+        response = _network.send_message(message, sizeof(calc_t));
+    } while (response.size() == 0 || response[0] + 1 != response.size());
+
+    vector<calc_t> res;
+    for (size_t i = 1; i < response.size(); i++) {
+        res.push_back((calc_t)response[i]);
+    }
+    return res;
+}
+
+void Client::calculate(calc_t n) const
+{
+    vector<uint64_t> message;
+    message.push_back((uint64_t)CODE_CALCULATE);
+    message.push_back((uint64_t)n);
+
+    vector<uint64_t> response;
+    do {
+        response = _network.send_message(message, sizeof(calc_t));
+    } while (response.size() != 1);
+
+    calc_t start_num = (calc_t)response[0];
+
+    vector<uint64_t> prime_nums = SimpleChecker::check_interval(start_num, n);
+
+    message.clear();
+    message.push_back((uint64_t)CODE_SEND_CALCULATED);
+    message.push_back((uint64_t)n);
+    message.push_back((uint64_t)start_num);
+    message.push_back((uint64_t)prime_nums.size());
+    for (uint64_t x : prime_nums) {
+        message.push_back(x);
+    }
+
+    do {
+        response = _network.send_message(message, sizeof(calc_t));
+    } while (response.size() != 0);
+}
\ No newline at end of file
diff --git a/03_UDP/src/Network.cpp b/03_UDP/src/Network.cpp
new file mode 100644
index 0000000..8f6a2c9
--- /dev/null
+++ b/03_UDP/src/Network.cpp
@@ -0,0 +1,121 @@
+#include "Network.h"
+
+using std::vector;
+using std::string;
+
+Network::Network(string host_name, uint16_t port)
+: _host_name(host_name), _port(port)
+{}
+
+int Network::try_send_message(char* message, size_t message_length, char* response) const
+{
+    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (sockfd < 0) {
+        throw NetworkException("Could not open socket");
+    }
+
+    struct hostent *server = gethostbyname(_host_name.c_str());
+
+    if (server == NULL) {
+        throw NetworkException("Could not find host");
+    }
+
+    struct sockaddr_in serv_addr;
+    memset((char*)&serv_addr, 0, sizeof(serv_addr)); 
+    serv_addr.sin_family = AF_INET; 
+    bcopy(server->h_addr, (char*) &serv_addr.sin_addr.s_addr, (size_t) server->h_length);
+    serv_addr.sin_port = htons(_port);
+
+    struct timeval tv;
+    tv.tv_sec = TIME_OUT_SEC;
+    tv.tv_usec = 0;
+    if (setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {
+        throw NetworkException("Could not set timeout");
+    }
+
+    int n;
+    n = sendto(sockfd, (const char *)message, message_length, MSG_CONFIRM, (const struct sockaddr *) &serv_addr, sizeof(serv_addr));
+    if (n == -1) {
+        close(sockfd);
+        return -1;
+    }
+
+    socklen_t len;
+    n = recvfrom(sockfd, (char *)response, MAX_LEN, MSG_WAITALL, (struct sockaddr *) &serv_addr, &len);
+  
+    close(sockfd);
+    return n; 
+}
+
+uint64_t Network::get_check_sum(const vector<uint64_t> &v, size_t prefix_length) const 
+{
+    size_t len = v.size();
+    if (len > prefix_length) {
+        len = prefix_length;
+    }
+
+    uint64_t sum = 0;
+    for (size_t i = 0; i < len; i++) {
+        sum += v[i];
+    }
+
+    return sum;
+}
+
+size_t Network::data2message(const vector<uint64_t> &message_data, size_t size_num, char* message) const
+{
+    char* pointer = message;
+    for (uint64_t x : message_data) {
+        bcopy((const char *)&x, pointer, size_num);
+        pointer += size_num;
+    }
+
+    uint64_t sum = get_check_sum(message_data, message_data.size());
+    bcopy((const char *)&sum, pointer, size_num);
+    pointer += size_num;
+
+    return size_num * (message_data.size() + 1);
+}
+
+int Network::massage2data(char* response, int response_length, size_t size_num, vector<uint64_t> &response_data) const
+{
+    if (response_length == -1 || response_length == 0) {
+        return -1;
+    }
+
+    if (response_length % size_num != 0) {
+        return -1;
+    }
+
+    char* pointer = response;
+    response_length /= size_num;
+    while (response_length--) {
+        uint64_t x;
+        bcopy(pointer, (char *)&x, size_num);
+        pointer += size_num;
+        response_data.push_back(x);
+    }
+
+    if (response_data.back() != get_check_sum(response_data, response_data.size() - 1)) {
+        return -1;
+    }
+
+    response_data.pop_back();
+
+    return 0;
+}
+
+vector<uint64_t> Network::send_message(const vector<uint64_t> &message_data, size_t size_num) const
+{
+    char message[MAX_LEN];
+    size_t message_length = data2message(message_data, size_num, message);
+
+    char response[MAX_LEN];
+    int response_length;
+    vector<uint64_t> response_data;
+    do {
+        response_length = try_send_message(message, message_length, response);
+    } while (massage2data(response, response_length, size_num, response_data) == -1);
+
+    return response_data;
+}
\ No newline at end of file
diff --git a/03_UDP/src/SimpleChecker.cpp b/03_UDP/src/SimpleChecker.cpp
new file mode 100644
index 0000000..c351580
--- /dev/null
+++ b/03_UDP/src/SimpleChecker.cpp
@@ -0,0 +1,27 @@
+#include "SimpleChecker.h"
+
+using std::vector;
+
+bool SimpleChecker::is_prime(uint64_t n)
+{
+    if (n < 2)
+        return false;
+
+    for (uint64_t d = 2; d*d <= n; d++)
+        if ((n / d) * d == n)
+            return false;
+    return true;
+}
+
+vector<uint64_t> SimpleChecker::check_interval(uint64_t start_num, size_t n)
+{
+    vector<uint64_t> res;
+
+    for (size_t dx = 0; dx < n; dx++) {
+        size_t x = start_num + dx;
+        if (is_prime(x))
+            res.push_back(x);
+    }
+
+    return res;
+}
\ No newline at end of file
diff --git a/03_UDP/src/main.cpp b/03_UDP/src/main.cpp
new file mode 100644
index 0000000..f31c286
--- /dev/null
+++ b/03_UDP/src/main.cpp
@@ -0,0 +1,89 @@
+#include <iostream>
+#include <tuple>
+#include <vector>
+#include <string>
+#include "Client.h"
+
+using namespace std;
+
+static const calc_t MAX_N = 50;
+
+tuple<string, uint16_t> read_addres() 
+{
+    string host_name;
+    uint16_t port;
+
+    cout << "Enter host name and port" << endl;
+    cin >> host_name >> port;
+
+    return make_tuple(host_name, port);
+}
+
+void print_commands()
+{
+    cout << endl;
+    cout << "List of commands:" << endl;
+    cout << "1. get_max_prime" << endl;
+    cout << "2. get_last_n <n>" << endl;
+    cout << "3. calculate <n>" << endl;
+    cout << "4. exit" << endl;
+    cout << endl;
+}
+
+string read_command()
+{
+    cout << endl;
+    cout << "Enter command" << endl;
+    string command;
+    cin >> command;
+    return command;
+}
+
+int main() 
+{
+    try {
+        string host_name;
+        uint16_t port;
+        tie(host_name, port) = read_addres();
+        Client client(host_name, port);
+
+        print_commands();
+
+        while (true) 
+        {
+            string command = read_command();
+            if (command == "get_max_prime") {
+                calc_t x = client.get_max_prime();
+                cout << x << endl;
+            } else if (command == "get_last_n") {
+                calc_t n;
+                cin >> n;
+                if (n > MAX_N) {
+                    cout << "n should not be more than " << MAX_N << endl;
+                    continue;
+                }
+                vector<calc_t> v = client.get_last_n(n);
+                for (calc_t x : v)
+                    cout << x << " ";
+                cout << endl;
+            } else if (command == "calculate") {
+                calc_t n;
+                cin >> n;
+                if (n > MAX_N) {
+                    cout << "n should not be more than " << MAX_N << endl;
+                    continue;
+                }
+                client.calculate(n);
+                cout << "Calculations completed" << endl;
+            } else if (command == "exit") {
+                break;
+            } else {
+                cout << "This is an unknown command" << endl;
+            }
+        }
+    } catch (NetworkException &e) {
+        cout << e.get_message() << endl;
+    }
+
+    return 0;
+}
\ No newline at end of file