#include <stdio.h>
#include <stdlib.h>
#include <wait.h>
#include <unistd.h>
#include <fcntl.h>

enum
{
    MODE = 0666,
};

int
main(int argc, char **argv)
{
    int fd[2];
    pipe(fd);

    pid_t pid12 = fork();
    if (pid12 < 0) {
        _exit(0);
    } else if (!pid12) {
        if (close(fd[0]) < 0 || dup2(fd[1], 1) < 0 || close(fd[1]) < 0) {
            _exit(1);
        }
        pid_t pid1 = fork();
        if (pid1 < 0) {
            _exit(0);
        } else if (!pid1) {
            int in1 = open(argv[4], O_RDONLY);
            if (in1 < 0 || dup2(in1, 0) < 0 || close(in1) < 0) {
                _exit(1);
            }
            execlp(argv[1], argv[1], NULL);
            _exit(1);
        } else {
            int status;
            wait(&status);
            if (!WIFEXITED(status) || WEXITSTATUS(status)) {
                _exit(0);
            }
            pid_t pid2 = fork();
            if (pid2 < 0) {
                _exit(0);
            } else if (!pid2) {
                execlp(argv[2], argv[2], NULL);
                _exit(1);
            } else {
                wait(NULL);
                _exit(0);
            }
        }
    } else {
        pid_t pid3 = fork();
        if (pid3 < 0) {
            _exit(0);
        } else if (!pid3) {
            if (close(fd[1]) < 0 || dup2(fd[0], 0) < 0 || close(fd[0]) < 0) {
                _exit(1);
            }
            int out3 = open(argv[5], O_CREAT | O_APPEND | O_WRONLY, MODE);
            if (out3 < 0 || dup2(out3, 1) < 0 || close(out3) < 0) {
                _exit(0);
            }
            execlp(argv[3], argv[3], NULL);
            _exit(1);
        } else {
            close(fd[0]);
            close(fd[1]);
            while (wait(NULL) != -1);
            exit(0);
        }
    }
}