#include<bits/stdc++.h>

using namespace std;

int main(){

    int s,v,total=1440,m,h;

    cin>>s>>v;

    float t;

    t=s/v;

    t=ceil(t);

    total=total-(int)t-10;

    h=total/60;

    if(h<=15)h=h+8;

    h=h-16;

    m=total%60;

    if(h<10)cout<<"0"<<h<<":"<<m;

    cout<<h<<":"<<m;

    exit(0);

}