text: #include "types.h"
  #include "user.h"
  #include "syscall.h"
  
  int main (void)
  {
    int rc;
    uint start_ticks = uptime();
    rc = fork();
    if (0 > rc){
      printf(2, "ERROR: fork failed.\n");
      exit();
    }
    if (0 == rc){
      rc = fork();
      if (0 > rc){
        printf(2, "ERROR: fork failed.\n");
        exit();
      }
      else{
        while(6000 > uptime() - start_ticks)
          ;
      }
    }
    wait();
    exit();
   }
  