C++ :

#include <cstdio>
#include <string>
#include <iostream>
using namespace std;
string f(char c){
    if(c == 'A') return "A";
    string p = f((char)(c - 1));
    string s(1, c);
    return s + p + s + p + s;
}
int main(){
    char c[8]; if(scanf("%s", c) != 1) return 0;
    cout << f(c[0]) << endl;
    return 0;
}