/*sivann@cs.ntua.gr*/
#include <stdio.h>
#include <time.h>

main(int argc, char **argv)
{
  time_t t;
  
  if (argc!=2) {
    printf("Usage: ctime <seconds since epoch>\n");
    exit(1);
  }
  t=atol(argv[1]);
  if (t<=0) {
    printf("Usage: ctime <seconds since epoch>\n");
    exit(1);
  }
  printf("%s",ctime(&t));
}