#include<iostream>
#include<cmath>
using namespace std;
int main() {
	int s,v,t;
	cin>>s>>v;
	if(s%v==0){
	  t=s/v+10;	
	}
	else {
		t=s/v+11;
	}
	
	if(t>=10&&t<60){
		cout<<"07:"<<60-t<<endl;
	}
	else if(t>60&&t<=8*60){
		if(t%60!=0&&t%60<=50){
			cout<<"0"<<8-t/60-1<<":"<<60-t%60<<endl;
		}
		else if(t%60!=0&&t%60>50){
			cout<<"0"<<8-t/60-1<<":0"<<60-t%60<<endl;
		}
		else if(t%60==0){
			cout<<"0"<<8-t/60<<":00"<<endl;
		}
	}
	else if(t>8*60){
		if(t%60!=0&&t%60<=50){
			cout<<8-t/60-1+24<<":"<<60-t%60<<endl;
		}
		else if(t%60!=0&&t%60>50){
			cout<<8-t/60-1+24<<":0"<<60-t%60<<endl;
		}
		else if(t%60==0){
			cout<<8-t/60+24<<":00"<<endl;
		}
	}
	else if(t=60){
		cout<<"07:00"<<endl;
	}
    return 0;
}