#include <iostream>
#include<string>

using namespace std;


main(){
	int h,m;
	char f;
	
	cin >> h >> f >>m;
	
	if(m<55){
		m=m+5;
		
	}else {
		m=m-55;
		if(h!=23)
			h++;
		else
			h=0;
	}
	
	cout<<h/10<<h%10<<":"<<m/10<<m%10<<endl;
	return 0;
}