#include <cstdio>
#include <vector>
#include <set>
#include <map>
#include <string>
#include <cstring>
#include <iostream>
#define SIZE(x) ((int) (x).size())
#define For(i, n) for (int i = 0; i < (int) (n); ++i)
using namespace std;

char key[1047];
char plain[100047];
int K,P;
char z;

int main() {
	while(1){
		scanf("%s",key);
		if (key[0]=='0') return 0;
		scanf("%s", plain);
		K = strlen(key);
		P = strlen(plain);
		For(i, P){
			z = (plain[i]-'A'+key[i%K]-'A'+1)%26+'A';
			printf("%c",z);
		}
		printf("\n");
	}

}