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

void solve(){
}

int main(){
    string a,b;
    cin>>a>>b;
    int ans = 0;
    while(a.size()!=b.size()){
        if(a.size()>b.size()) b = string(1,'0') + b;
        else a = string(1,'0') + a;
    }

    for(int i = 0;i<a.size();i++){
        int ni = a[i] - '0';
        int nj = b[i] - '0';
        ni += nj;
        ni %= 2;
        ans *= 2;
        ans += ni;
    }
    cout<<ans<<endl;
}