#include <cstdio>
  
#include <cmath>  
int main (){
  
	int s,v,t,k;
  
	double n,a,b;
  
	scanf("%d%d",&s,&v);
  
	a=1.0*s;
  
	b=1.0*v;
  
	n= a/b;
  
	k= ceil (n);
  
	t= k+10;
  
	if (t<480){
                
		if (t%60==0){
                
			printf ("0%d:00",7-t/60);
                
		}else {
                
			printf("0%d:%d",7-t/60,60-t%60);
                
		}
		
	}if (t==480){
                
        printf("00:00");
                }
                
	if (t >480){
  
		if (t%60==0){
  
			printf ("%d:00",24-(t/60-8));
  
		}else {
  
			printf("%d:%d",23-(t/60-8),60-t%60);
  
		}
  
	}
  
	return 0;}