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

int
main(int argc, char *argv[])
{
    int fdp[2];
    pipe(fdp);
    int status;
    if (fork() == 0) {
        pid_t pid;
        if ((pid = fork()) == 0) {
            int in = open(argv[4], O_RDONLY);
            close(fdp[0]);
            dup2(in, 0);
            dup2(fdp[1], 1);
            close(in);
            execlp(argv[1], argv[1], NULL);
            _exit(1);
        }
        waitpid(pid, &status, 0);
        if (WIFEXITED(status) && !WEXITSTATUS(status)) {
            if (fork() == 0) {
                close(fdp[0]);
                dup2(fdp[1], 1);
                execlp(argv[2], argv[2], NULL);
                _exit(1);
            }
        }
        _exit(0);
    }
    close(fdp[1]);
    if (fork() == 0) {
        int out = open(argv[5], O_WRONLY | O_CREAT | O_APPEND, 0660);
        dup2(fdp[0], 0);
        dup2(out, 1);
        close(out);
        execlp(argv[3], argv[3], NULL);
        _exit(1);
    }
    close(fdp[0]);
    while (wait(NULL) != -1) {}
    return 0;
}