#include <iostream>
#include <string>

using namespace std;

int main() {
	int n; cin >> n;
	string s; cin >> s;
	for(unsigned char ch : s) { // 防溢出 
		ch -= 'a';
		ch += n;
		ch %= 26;
		ch += 'a';
		cout << (char)ch;
	}
	
	return 0;
}