#include<bits/stdc++.h>
using namespace std;
int main()
{
    int s, v;
    cin >> s >> v;
    int n1 = 0;
    if(s%v==0)
    {
        n1 = s / v;
    }
    else
       { n1 = s / v + 1;}
       int n = 480 - n1-10;
       cout <<"0"<<n / 60 << ":" << n % 60;
       return 0;
}