#include<iostream>
#include<cmath>
#include<iomanip>
using namespace std;
int main (){
	int er,s,v,t,sum;
	cin>>s>>v;
	if(s%v==0) t=s/v+10;
	else t=s/v+11;
	sum=480-t;

	
if(sum%60>=10)
cout<<"0"<<sum/60<<":"<<sum%60;
else cout<<"0"<<sum/60<<":"<<"0"<<sum%60;

return 0;
}