#include<iostream>
#include<cmath>
using namespace std;
int main(){
    double s,v;
    cin>>s>>v;
    double z=s/v+10;
    int x=ceil(8*60-z-1);
    int ss=x/60,f=x%60;
    printf("%02d:%02d",ss,f);
    return 0;
}