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

int main(int argc, char *argv[])
{
    int fd[2];
    pipe(fd);
    int pid;
    if ((pid = fork()) == 0) {
        dup2(fd[1], 1);
        close(fd[0]);
        close(fd[1]);
        pid_t pid2;
        if ((pid2 = fork()) == 0) {
            int file1 = open(argv[4], O_RDONLY);
            dup2(file1, 0);
            close(file1);
            execlp(argv[1], argv[1], NULL);
            _exit(1);
        }
        int status;
        wait(&status);
        if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
            if ((pid2 = fork()) == 0) {
                execlp(argv[2], argv[2], NULL);
                _exit(1);
            }
        }
        wait(NULL);
        wait(NULL);
        exit(1);
    }
    if ((pid = fork()) == 0) {
        dup2(fd[0], 0);
        close(fd[0]);
        close(fd[1]);
        int file2 = open(argv[5], O_WRONLY | O_APPEND | O_CREAT, 0666);
        dup2(file2, 1);
        execlp(argv[3], argv[3], NULL);
        exit(1);
    }
    close(fd[0]);
    close(fd[1]);
    while (wait(NULL) > 0) {}
    return 0;
}