#include "bits/stdc++.h"
using namespace std;
#define ll long long int
#define rep(i,n) for( int i = 0; i < n; i++ )
#define rrep(i,n) for( int i = n; i >= 0; i-- )
#define REP(i,s,t) for( int i = s; i <= t; i++ )
#define RREP(i,s,t) for( int i = s; i >= t; i-- )
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define INF 2000000000
#define mod 1000000007
#define INF2 1000000000000000000


int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
	int a, b; cin >> a >> b;
	string S; cin >> S;
	S = S.substr(3);
	double c = stod(S);
	c += 15;
	int minutes = a * 60 + b + (int)(c * 60 + 0.5);
	//cout << minutes << endl;
	while (minutes >= 24 * 60) minutes -= 24 * 60;
	cout << setfill('0') << right;
	cout << setw(2) << minutes / 60 << ":" << setw(2) << minutes % 60  << endl;

    return 0;
}