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

int main()
{
	int N;
	string S;
	cin >> N >> S;

	vector<int> a( N, 25 );
	for( int i = 0; i < N; i++ ) a[i] -= S[i] - 'a';
	string ans;
	for( int i = 0; i < N; i++ ) ans += (char)(a[i] + 'a');

	cout << ans << endl;
}