#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
using ll = int_fast64_t;
using ull = uint_fast64_t;

using mint = modint998244353;

constexpr ll INF = 1ll << 60;

template<typename T, typename D> void printelem(const T& container, const D& divide){
	for(const auto& i : container) cout << i << divide;
	cout << endl;
}
template<typename T> void printelem(const T& container) { printelem(container, ", "); }

int main(){
	//インプット
	string A, B;
	cin >> A >> B;

	ll a = 0, b = 0;
	for(char i : A){
		a <<= 1;
		a += (i == '1');
	}
	for(char i : B){
		b <<= 1;
		b += (i == '1');
	}

	//アウトプット
	cout << (a ^ b);
	
	return 0;
}