#include <iostream>

using namespace std;
int main()
{
    int n,c,a;
    string s;
    cin>>c;
    cin>>s;
    n = s.length();
    for(int i = 0;i<n;i++){
        if(s[i]=='y'){
            cout<<'a';
        }
        else if(s[i]=='z'){
            cout<<'b';
        }
        else{
        a = (int)s[i] + c;
        cout<< (char)a;}
    }
    return 0;
}


