#include <iostream>
#include <string>
#include <map>

using namespace std;

string n_to_letter{"ABCDEFGHIJKLMNOPQRSTUVWXYZ"};
map<char, int> letter_to_n;
string key;

void build_letter_to_n()
{
  for (int i = 0; i < n_to_letter.size(); ++i)
    letter_to_n[n_to_letter[i]] = i;
}

string cipher(string in)
{
  string out;
  for (int i = 0; i < in.size(); ++i)
  {
    int n = letter_to_n[in[i]];
    int k = letter_to_n[key[i % key.size()]];
    n = (n + k) % n_to_letter.size();
    out += n_to_letter[n];
  }

  return out;
}

int main()
{
  cin >> n_to_letter; // alphabet

  build_letter_to_n();

  cin >> key;

  string in;
  cin >> in;

  cout << cipher(in);

  return 0;
}