#include <stdio.h>
#include <math.h>
int main()
{	int p;
	double s,v;
	scanf("%lf%lf",&s,&v);
	p=ceil(s/v)+10;
	if (p<480)
		if (p%60==0)
			printf("%d%d:%d%d",0,8-p/60,0,0);
		else
			printf("%d%d:%d",0,8-p/60-1,60-p%60);
	else 
		if (p%60==0)
			printf("%02d:%d%d",24-p/60+8,0,0);
		else
			printf("%02d:%d",24-p/60+7,60-p%60);
	return 0;	
}
```c