Reloj - CodeForces

#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<cstdlib>
#include<vector>
#define db(a) cout << #a << " = " << a << endl;
#define db2(a, b) cout << #a << " = " << a << "  " << #b << " = " << b << endl;
#define foreach(it, l) for(typeof(l.begin()) it = l.begin(); it != l.end(); it++)
using namespace std;
string reves(int a) {
	char arr[10];
	sprintf(arr, "%02d", a);
	int len = strlen(arr);
	reverse(arr , arr + len);
	return arr;
}
int main() {
	int H, M;	
	string hora;
	while(cin >> hora) {
		char res[10];
		bool find = false, first = true;
		sscanf(hora.c_str(), "%d:%d", &H, &M);
		for (int h = 0; h < 24 && !find; h++) {
			int m = 0;
			if(first) {
				m = M + 1;
				first = false;
			}
			for (; m < 60 && !find; m++) {
				char mc[10];
				sprintf(mc, "%02d", m);
				if(reves((h + H) % 24) == mc) 
				sprintf(res, "%02d:%02d", (h + H) % 24, m), find = true;
			}
		}
		cout << res << endl;
	}
	return 0;
}