#include <cstdio>
#include <cstring>

using namespace std;

char plain[100048];

int main(){
    char  key[1024];
    scanf("%s ",key);
    while(strcmp(key,"0")!=0){
        scanf("%s ",plain);
        int n=strlen(key);
        for(int i=0; i<strlen(plain); i++){
            char cip=(plain[i]+key[i%n]-2*('A'))%26+'B';
            if(cip==('Z'+1))
                cip='A';
            printf("%c",cip);
        }
        printf("\n");

        scanf("%s ",key);
    }


}