#include <iostream>
#include <string>

using namespace std;

int main(){
    string s, ans;
    cin >> s;
    
    bool na = false;
    for (int i = 0; i < s.size(); i++){
        if(na == false) ans.push_back('a');
        if (s[i] != 'a') na = true;
    }
    
    if (na == false) ans.push_back('a');
    
    cout << ans << endl;
}