60分

#include<bits/stdc++.h>

using namespace std;

int main() {
    string s;
    int a;
    cin >> a >> s;
    for (int i = 0; i < s.size(); i++) {
        s[i] += a;
        if (s[i] > 'z') {
            s[i] -= 26;
        }
    }
    cout << s;
    return 0;
}