import java.util.*;
import java.io.*;

public class vigenere{


public static void main(String[] args) throws IOException{
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String line;
	String zacetniKljuc;
	String kljuc;
	String beseda;
	String resitev;
	int novaCrka;
	int novaCrka1;
	int novaCrka2;
	char crka;
	while(!(line = br.readLine()).equals("0")){
		resitev = "";
		zacetniKljuc = line;
		kljuc = zacetniKljuc;
		beseda = br.readLine();
		novaCrka = 0;
		novaCrka1 = 0;
		novaCrka2 = 0;
		for(int i = 0; i < beseda.length(); i++){
			novaCrka = (int)kljuc.charAt(i % kljuc.length()) - 64;
			novaCrka1 = (int)beseda.charAt(i) - 64;
			crka = (char)novaCrka;
			novaCrka2 = ((novaCrka + novaCrka1) % 26) + 64;
			if(novaCrka2 == 64){
				novaCrka2 = 90;
			}
			resitev = resitev + (char)novaCrka2;
		}
		System.out.println(resitev);
	}	

}



}