#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <memory.h>
using namespace std;

char key[2010], text[2010];

int c(char z) {
    if ('0' <= z && z <= '9') return z - '0';
    return z - 'a' + 10;
}

int main() {
    scanf("%s", key);
    scanf("%s", text);
    int k = strlen(key);
    int n = strlen(text);
    int j = 0;
    for (int i = 0; i < n; i += 2) {
        int code = c(text[i]) * 16 + c(text[i+1]);
        // printf("%d ", code);
        
        code ^= key[j];
        j = (j + 1) % k;
        putchar(code);
    }
    return 0;
}