#include <bits/stdc++.h>
using namespace std;
const int MAXX = 10005;

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    string s;
    cin >> s;
    vector <char> v;
    char last = s[0];
    v.push_back(last);
    for(int i = 1; i < s.length(); i++) {
        if(s[i] == last) continue;
        else {
            last = s[i];
            v.push_back(last);
        }
    }
    if(v.size() < 3) for(auto x: v) cout << x;
    else if(v.size() % 2 == 1) cout << v[0] << v[1] << v[2];
    else cout << v[0] << v[1];
    cout << endl;

}


/*

10110

1010


*/