#include <stdio.h>
#include <string.h>

typedef unsigned int uint;

int main(void) {
    char key[1001]={'0'}, text[100001];
    uint ki, ti;
    size_t kl, tl;
    
    while (1) {
        scanf("%s\n", key);
        if (key[0]=='0') break;
        scanf("%s\n", text);
        ki = ti = 0;
        kl = strlen(key);
        tl = strlen(text);
        while (tl--) {
            printf("%c", ((key[ki++]-'A'+1) + (text[ti++]-'A'+1) - 1)%('Z'-'A'+1) + 'A');
            ki %= kl;
        }
        printf("\n");
    }
    return 0;
}