A

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <set>
#include <stack>
#include <queue>
#include <deque>
using namespace std;

#define TASK "negcycle"

string s;
char minb[200000];
int nom[200000], mind, maxk, n, idx;

int main() {

#ifdef _DEBUG
    freopen("debug.in", "r", stdin);
    freopen("debug.out", "w", stdout);
#else
    freopen(TASK".in", "r", stdin);
    freopen(TASK".out", "w", stdout);
    //freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
#endif // _DEBUG

    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cout.precision(6);


    cin >> s;
    n = s.size();
    minb[0] = s[0];
    nom[0] = 0;
    for (int i = 1; i<n; i++)
    {
        if (s[i] <= minb[i - 1])
        {
            minb[i] = s[i];
            nom[i] = i;
        }
        else
        {
            minb[i] = minb[i - 1];
            nom[i] = nom[i - 1];
        }
    }
    maxk = s[n - 1] - minb[n - 1];
    idx = nom[n - 1];
    mind = n - nom[n - 1];
    for (int i = n - 2; i >= 0; i--)
    {
        if (s[i] - minb[i]==maxk && mind > i - nom[i] || s[i] - minb[i] > maxk)
        {
            idx = nom[i];
            mind = i - nom[i] + 1;
            maxk = s[i] - minb[i];
        }
    }
    cout << s.substr(idx, mind);

    return 0;
}