#include<iostream>
using namespace std;

int main()
{
    int s,v;
    cin>>s>>v;
    int time=s/v+10;
    if(s%v!=0)  time++;
    time=480-time;
    int h=time/60,m=time%60;

    cout.width(2);
    cout.fill('0');
    cout<<h<<':';
    cout.width(2);
    cout<<m;

    cin.get();cin.get();
    return 0;
}