#include <stdio.h>
int main()
{
  int s, v;
  scanf("%d%d", &s, &v);
  int m, h;
  if(s % v) m = s / v + 1 + 10;
  else m = s / v + 10;
  h = m / 60;
  m %= 60;
  if (h >= 24) h -= 24;
  if (h >= 8&&h<24)
  {
    if (h == 8 && m == 0) printf("00:00");
    else if (h >= 22)
    {
      if (h == 22 && m == 0) printf("10:00");
      else printf("0%d:%d",24-h+7,60-m);
    }
    else
    {
      printf("%d:%d", 23 - (h - 8), 60 - m);
    }
  }
  else
  {
    printf("0%d:%d", 7 - h, 60 - m);
  }
  return 0;
}