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

int main(){
    string s1,s2;
    cin >> s1 >> s2;
    int l1,l2;
    l1 = s1.length();l2=s2.length();
    ll ans=0;
    int m = max(l1,l2);
    if(l1<l2){
        while(l1<m){
            ans*=2;
            if(s2[0] == '1'){
                ans+=1;
            }
            m--;
            s2.erase(s2.begin());
        }
    }else{
        while(l2<m){
            ans*=2;
            if(s1[0] == '1'){
                ans+=1;
            }
            m--;
            s1.erase(s1.begin());
        }
    }
    for(int i=0;i<min(l1,l2);i++){
        int ch = 0;
        if(s1[i] == '1' && s2[i] == '1'){
            
        }else if(s1[i] == '0' && s2[i] == '0'){

        }
        else{
            ch = 1;
        }
        ans *= 2;
        ans += ch;
    }
    cout << ans << endl;
}