#include<bits/stdc++.h>
using namespace std;
int h,m,t;
double s,v;                       
int main()
{
	cin>>s>>v;
    t=ceil(s/v)+10;
    if(t<=480){
        t=480-t;
    }
    else if(t>480 and t<=1440){
        t=24*60+480-t;
    }
    
    h=t/60;
    m=t%60;
    cout<<"0"<<h<<":"<<m;


	return 0;
}