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

int main()
{
	int kyori,sokudo,zikann;
	scanf("%d%d",&kyori,&sokudo);
	zikann = kyori/sokudo;
	if(kyori%sokudo) zikann++;
	time(zikann+10);
	return 0;
 } 
 
 void time(int t)
 {
 	int h = 7;
 	while(t >= 60)
 	{
 		t-=60;
 		h--;
 		if(h<0) h+=24;
	 }
	printf("%02d:%2d",h,60-t);
 }

卡在70分了，求助