import java.io.*;
// import java.math.*;
// import java.util.*;
// import java.util.Map.*;
// import java.util.stream.*;

public class Main {
    public static void main (String[] args) throws Exception {
        BufferedReader reader =
            new BufferedReader (new InputStreamReader (System.in));
        int N = Integer.parseInt (reader.readLine());
        String S = reader.readLine();
        String alp = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        System.out.println (
            trans (S, alp, alp.substring (N) + alp.substring (0, N)));
        return;
    }

    static String trans (String S, String f, String t) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < S.length(); i++) {
            int idx = f.indexOf (S.charAt (i));
            sb.append (t.charAt (idx));
        }
        return sb.toString();
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz