#include <stdio.h>
#include <math.h>
int main()
{
	int s,v;
	scanf("%d %d",&s,&v);
	double t=1.0*s/v;
	double a,c;
	int b;
	a=470.0-t;
	b=a/60;
	c=fmod(a,60);
	int d;
	d=(int)c;
	if(d>10) 
	printf("0%d:%d",b,d);
	else{printf("0%d:0%d",b,d);}
	return 0;
}