#include <bits/stdc++.h>
using namespace std;
int main(){
    int a,b,s,u;
    cin>>s>>u;
    int c=s/u+s%u+10;
    int d=c/60;
    c=c%60;
    if(d<8){
        b=60-c;
        a=8-d;
    }
    else if(d==8&&c==0){
		cout<<"00:00";
		return 0;
	}
    else {
        d=d-8;
        b=60-c;
        a=24-d;
    }
    if(b==60){
		b=0;
	}
    if(c!=0){
	    a=a-1;
	}
    if(a<10) cout<<0;
	cout<<a<<':';
	if(b<10){
	  cout<<0;
	}
	cout<<b;
    return 0;
}