#include <bits/stdc++.h>
using namespace std;
const int N = 112345;
int a[N];
int b[N];

main()
{
    string s, t;
    cin >> s;
    int cnt = 0;
    int mx=0;
    int l=0;
int cnte=0;
    for(int i = s.size() - 1; i >= 0; i --)
    {
        t = s[i] + t;
        a[0] = 0;

        for(int j = 1; j < t.size(); j ++)
        {
            int x = a[j - 1];
            while(x > 0 && t[x] != t[j])
                x = a[x - 1];
            if(t[x] == t[j])
                x ++;
            a[j] = x;
            mx = max(mx, a[j]);

        }
            b[i]=mx;
            if(mx==0)cnte++;
            mx=0;

    }
    if(cnte==s.size()){cout<<s;return 0;}
    else
for(int i=0;i<s.size();i++){if(b[i]>=1)cout<<s[i];}


}
// any suggestion guys I have no idea what can be  the fifth test thanks in advance