#include <bits/stdc++.h>

using std::cin;
using std::cout;
using std::min;
using std::string;
using std::vector;
using P = std::pair<char, int>;

int main() {
	string s;
	cin >> s;
	int n = s.size();
	
	char t = s[0];
	for (int i = 1; i < n; ++i) t = min(t, s[i]);
	int p = s.find(t);
	
	int k = p + 1;
	while (s[k] == s[p]) ++k;
	
	string ans = s.substr(p, k) + "a";
	cout << ans << '\n';
	
	return 0;
}