#include <bits/stdc++.h>
using namespace std;

char digitos(char a, char b) {
    int da = a - '0';
    int db = b - '0';

    if ((da <= 2 && db <= 2) || (da >= 7 && db >= 7))
        return '0';
    else
        return '9';
}


string addCeros(const string& str, int length) {
    if (str.length() >= length)
        return str;

    return string(length - str.length(), '0') + str;
}

string xor10(const string& a, const string& b) {
    int maxLength = max(a.length(), b.length());

    string ca = addCeros(a, maxLength);
    string cb = addCeros(b, maxLength);

    string result;
    for (int i = 0; i < maxLength; ++i) {
        result += digitos(ca[i], cb[i]);
    }

    return result;
}

int main() {
    string a, b;
    cin >> a >> b;

    string res = xor10(a, b);
    cout << res << endl;

}