#include <stdio.h>

const int daysInMonth[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

int main ()
{
   int dd, mm, yyyy, h, m, s, i;
   int nsecs, ndays;

   printf("Enter system time in seconds : "); scanf("%d", &nsecs);
   yyyy = 1970;
   dd = nsecs / 86400;
   while (1) {
      ndays = (yyyy % 4 == 0) ? 366 : 365;
      if (dd >= ndays) { ++yyyy; dd -= ndays; } else { break; }
   }
   for (i=1; i<=12; ++i) {
      ndays = daysInMonth[i-1];
      if ((i == 2) && (yyyy % 4 == 0)) ++ndays;
      if (dd < ndays) { mm = i; ++dd; break;}
      else dd -= ndays;
   }
   s = nsecs % 86400;
   h = s / 3600; s %= 3600;
   m = s / 60; s %= 60;
   printf("Time (dd-mm-yyyy hh:mm:ss) is %s%d-%s%d-%d %s%d:%s%d:%s%d\n",
      (dd < 10) ? "0" : "", dd, (mm < 10) ? "0" : "", mm, yyyy,
      (h < 10) ? "0" : "", h, (m < 10) ? "0" : "", m, (s < 10) ? "0" : "", s);
}