#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    string s; cin >> s;
    int d = 1;
    for(auto &c : s) c = (c-'A'-d+26)%26+'A',d = (d+1)%26;
    cout << s << endl;
}