#include <iostream>
#include <string>
using namespace std;
using ll = long long;
int main()
{
    string s;
    ll x;
    cin>>x;
    cin>>s;
    for(int i = 0;i < s.length();i++)
    {
        cout<<char( (s[i]-'a'+x)%26+'a');
    }
    return 0;
}