#include <iostream>
#include <string>
using namespace std;
int main(){
string s;
getline(cin, s);
bool inainteDeA = true;
for(int i = 0; i < s.length(); i++){
if(s[i] == 'a'){
if(!inainteDeA) {cout << "EROARE: doua caractere 'a' au fost gasite\n";return -2;}
inainteDeA = false;
}
else{
if(inainteDeA)s[i] = 'b';
else s[i] = 'c';
}
}
if(inainteDeA){cout << "EROARE: Niciun caracter 'a' nu a fost gasit"; return -1;}
cout << s;
}
