#include<bits/stdc++.h>
using namespace std;
int main(){
	long a,b,s,v,t,sumt;
	cin>>s>>v;
	t=s*1.000000/v;
	sumt=t+10;
	a=sumt/60;
	b=sumt%60;
	if(8-a<=0&&59-b>=10)cout<<23-(a-8)<<":"<<59-b;
	if(8-a<=0&&59-b<10)cout<<23-(a-8)<<":"<<"0"<<59-b;
	if(8-a>0&&8-a<10&&59-b>=10)cout<<"0"<<7-a<<":"<<59-b;
	if(8-a>0&&8-a<10&&59-b<10)cout<<"0"<<7-a<<":"<<"0"<<59-b;
	return 0;
}