#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
constexpr int INF = 1e9;
constexpr long long LINF = 1e17;
constexpr int MOD = 1000000007;
constexpr double PI = 3.14159265358979323846;

int main(){
    string t;
    cin >> t;
    if(t.substr(0,2)=="23"&&"55"<=t.substr(3,2)&&t.substr(3,2)<="59"){
        t[0] = t[1] = t[3] = '0';
        t[4] = t[4] - '5' + '0';
    }else if("55"<=t.substr(3,2)&&t.substr(3,2)<="59"){
        if(t[1] =='9'){t[0]++;t[1]='0';}
        else t[1]++;
        t[3]='0';
        t[4] = t[4] - '5' + '0';
    }else{
        if('5'<=t[4]&&t[4]<='9'){t[3]++;t[4]=t[4] - '5' + '0';}
        else t[4] += 5;
    }
    cout << t << endl;

    return 0;
}