#include<iostream>
using namespace std;
int main(){
	int s,v,t;
	cin>>s>>v;
	if(s%v!=0){
		t=s/v+1;
	}else{
		t=s/v;
	}
	int t2=480-t-10;
	if(t2<0){
		t2=24*60+480-t-10;
	}
	int a=t2/60;
	int b=t2%60;
	if(a/10==0){
		cout<<"0"<<a<<":";
		if(b/10==0){
			cout<<"0"<<b;
		}
		else
		{
			cout<<b;
		}
	}
	else
	{
		cout<<a;
		if(b/10==0){
			cout<<"0"<<b;
		}else{
			cout<<b;
		}
	}
	return 0;
}