#include <cstdlib>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <cstring>
using namespace std;

static void solve()
{
	static char key[1001], buf[100001];
	scanf("%s", key);
	if (key[0] == '0') exit(0);
	scanf("%s", buf);
	int klen = strlen(key), blen = strlen(buf);
	for (int i=0,ki=0; i<blen; i++, ki=(ki+1)%klen)
		printf("%c",'A'+(buf[i]+key[ki]-2*'A'+1)%26);
	printf("\n");
}

int main(void) {
	for(;;) solve();
}