#include <unistd.h>
#include <sys/wait.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>

int main (int argc, char * argv[]) {
    int fd[2];
    pipe(fd);
    int pidSFir, pidSSec;
    if (!(pidSFir = fork())) {
        int pidGSFir, pidGSSec;
        close(fd[0]);
        dup2(fd[1], 1);
        close(fd[1]);
        if (!(pidGSFir = fork())) {
            execlp(argv[1], argv[1], NULL);
            return -1;
        }
        waitpid(pidGSFir, NULL, 0);
        if (!(pidGSSec = fork())) {
            execlp(argv[2], argv[2], NULL);
            return -1;
        }
        close(fd[1]);
        waitpid(pidGSSec, NULL, 0);
        _exit(0);
    }
    close(fd[1]);
    if (!(pidSSec = fork())) {
        int flDes = open(argv[4], O_WRONLY | O_CREAT | O_TRUNC, 0222);
        dup2(flDes, 1);
        close(flDes);
        dup2(fd[0], 0);
        close(fd[0]);
        execlp(argv[3], argv[3], NULL);
        return -1;
    }
    close(fd[0]);
    waitpid(pidSFir, NULL, 0);
    waitpid(pidSSec, NULL, 0);
    return 0;
}