70分，求救QAQ

#include <stdio.h>
#include <string.h>
#include <math.h>

int main() 
{
   int s , v;
   scanf("%d %d,",&s,&v);

   int time = 480 - ( ceil(s*1.0/v) + 10 );
   int hour = time/60 , minute = time - 60*hour;

   printf("0%d:%.2d",hour,minute);

    return 0;
}