#include<iostream>
using namespace std;
int main(){
	int s,v;
	cin>>s>>v;
	int t=s/v+1+10;
	int t2=t;
	int t60;
	int qq=8;
	while(114514){
		if((t60-t)<=0){
			qq--;
			t60+=60;
		}
		else {
			if(qq<0) qq+=24;
			if(qq<10&&(t60-t)<10){
				cout<<"0"<<qq<<":"<<"0"<<t60-t;
			}
			else if(qq<10){
				cout<<"0"<<qq<<":"<<t60-t;	
			}
			else if((t60-t)<10){
				cout<<qq<<":"<<"0"<<t60-t;
			}
			else cout<<qq<<":"<<t60-t;
		
			return 0;
		}
	}
	return 0;
}