#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
typedef long long ll;
double s,v;
ll hour=7,minute=50;
ll sp;
int main(){
	scanf("%lf%lf",&s,&v);
	sp+=ceil(s/v);
	hour -= sp/60;
	while(hour<0) hour+=24;
	minute -= sp%60;
	if(minute<0) minute+=60;
	if(hour<10) cout << "0";
	cout << hour << ":";
	if(minute<10) cout << "0";
	cout << minute;
	return 0;
}