#include <bits/stdc++.h>
using namespace std ;
int s,v;
int sum=10;
int main(){
    cin>>s>>v;
    sum+=s/v;
    int e=8-ceil(sum/60)-1,o=60-sum%60-1;
    if(s%v==0) o--;
    if(e<0){
        o++;
        while(e<0) e=24+e;
    }
    if(e>=10)
        cout<<e<<":";
    else
        cout<<"0"<<e<<":";

    if(o>=10)
        cout<<o;
    else
        cout<<"0"<<o;
	return 0;
}
//1000 12
//06:26
//1000 1
//15:10
//10000 5
//22:30