#include<bits/stdc++.h>
using namespace std;
int a,b,t;
int x=7,y=50,q,w;
int main(){
	cin>>a>>b;
	t=a/b;
	if(a%b!=0) t++;
	if(t>=480) {
		x=23;
		y=50;
	}
	w=abs(y-t);
	if(t>y&&t>=60) q=x-t/60;
	else
	if(q<10) cout<<0;
	cout<<x<<":";
	if(w<10) cout<<0;
	cout<<w;
}

30分，前三个点AC其他WA