#include <bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	string s;
	cin >> n;
	cin >> s;
	for (int i = 1;i <= s.size();i++)
	{
		s[i] += n;
		if (s[i] > 'z')
		{
			s[i] -= 'z';
			s[i] += 'a';
		}
	}
	cout << s;
	return 0;
}