#include<iostream>
#include<cmath>
#include<iomanip>
//用ceil
using namespace std;
int main(){
  int s,v,shi,fen,t;
  cin>>s>>v;
  // scanf("%d %d",&s,&v);
  t = ceil(s/v) + 10;
  if(t>480){
  shi = 24-(t-480)/60;
  fen = 60-t%60;
  }
  else{
    shi = 7-t/60;
    fen = 60-t%60;
  }
  cout<<setw(2)<<setfill('0')<<shi<<':'<<fen;
  return 0;
}