#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#include<cmath>
#include<vector>
#include<utility>
#include<stack>
#include<queue>
#include<list>

#define FOR(i, a, b) for(int i=(a);i<=(b);i++)
#define RFOR(i, a, b) for(int i=(a);i>=(b);i--)
#define MOD 1000000007
#define INF 1000000000

using namespace std;


int main(void) {
	char t[6];
	char s[6];

	s[2] = ':';
	s[5] = '\0';
	cin >> t;
	if (t[3] == '5'&&t[4] >= '5') {
		if (t[0] == '2'&&t[1] == '3') {
			s[0] = '0';
			s[1] = '0';
		}
		else if (s[1] == '9') {
			s[0] = t[0] + 1;
			s[1] = '0';
		}
		else {
			s[0] = t[0];
			s[1] = t[1] + 1;
		}
		s[3] = '0';
		s[4] = t[4] - 5;
	}
	else if (t[4] >= '5') {
		s[0] = t[0];
		s[1] = t[1];
		s[3] = t[3] + 1;
		s[4] = t[4] - 5;
	}
	else {
		s[0] = t[0];
		s[1] = t[1];
		s[3] = t[3];
		s[4] = t[4] + 5;
	}
	cout << s << endl;
	return 0;
}