#include <iostream>
#include<string>
using namespace std;
int main() {
string a,b;
cin>>a>>b;
string c;
int n= a.length();
for(int i=0;i<n;i++){
if(a[i]==b[i]) c+='0';
else c+='1';
}
// cout<<c;
stol(c);
cout<<c;
return 0;
}
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