#include <string>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <algorithm>
#include <list>
#include <map>
#include <iostream>
using namespace std;

string abc="ABCDEFGHIJKLMNOPQRSTUVWXYZ";

string plain, key;

int main() {
  while (1) {
    cin >> key;
    if (key == "0")
      return 0;
    cin >> plain;
    int tmp=0;
    for(int i=0; i<plain.length(); i++) {
      int ind =plain[i] -'A';
      ind = (ind +key[tmp%key.length()] -'A' +1)%26;
      cout << abc[ind];
      tmp ++;
    }
    cout << "\n";
  }
  
  return 0;
}