#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define SECS_PER_HOUR 3600

int main(int argc, char *argv[])
{
   int curr_time = (int)time(NULL);
   int h;
   int new_time;

   h = (argc == 2) ? atoi(argv[1]) : 0;

   new_time = curr_time - (h * SECS_PER_HOUR);

   printf("%s\n", asctime(localtime((time_t *)&new_time)));

   return 0;
}