#include <iostream>
using namespace std;
int main()
{
    int s, v,t,min=0,h=8;
    cin >> s >> v;
    t = s / v;
    if(s%v!=0)
        t++;
    t += 10;
    while (t)
    {
        if(min-1<0){
            min += 60;
            h--;
        }
        min--;
        t--;
    }
    while (h<=0)
    {
        h = 24 + h;
    }
    if (h<10)
    {
        cout << 0;
    }
    cout << h << ':' << min;
}