#define _GNU_SOURCE
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>
#include <netinet/in.h>
#include <stdint.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>


int main(int argc, char *argv[]) {
    int port_num = strtol(argv[1], NULL, 10);
    char* s_addr = "127.0.0.1";
    int sock = socket(AF_INET, SOCK_DGRAM, 0);

    struct sockaddr_in addr = {
            .sin_family = AF_INET,
            .sin_addr = inet_addr(s_addr),
            .sin_port = htons(port_num)
    };

    int num_in;
    int num_out;
    while(scanf("%d", &num_in) > 0) {
        sendto(sock, &num_in, sizeof(num_in), 0, (const struct sockaddr*)&addr, sizeof(addr));
        recvfrom(sock, &num_out, sizeof(num_out), 0, NULL, NULL);
        printf("%d\n", num_out);
    }
    close(sock);

}