#include<iostream>
using namespace std;
int s,v;
int tm;
int h,m;
int main()
{
        cin>>s>>v;
        if(s%v==0) tm=s/v;
        if(s%v!=0) tm=s/v+1;
        if(tm>470)
        {
            h=23-(tm-470)/60;
            m=60-(tm-470)%60;
            if(h<10) cout<<"0"<<h<<":";
            else cout<<h<<":";
            if(m<10) cout<<"0"<<m;
            else cout<<m;
        }
        if(tm==470) cout<<"24:00";
        if(tm<470)
        {
            h=7-tm/60;
            m=50-tm%60;
            if(m<10) cout<<"0"<<h<<":0"<<m;
            else cout<<"0"<<h<<":"<<m;
        }
}