#include<bits/stdc++.h> using namespace std; //#pragma GCC optimize("Ofast") #define rep(i,n) for(ll i=0;i<n;i++) #define repl(i,l,r) for(ll i=(l);i<(r);i++) #define per(i,n) for(ll i=(n)-1;i>=0;i--) #define perl(i,r,l) for(ll i=r-1;i>=l;i--) #define fi first #define se second #define pb push_back #define ins insert #define pqueue(x) priority_queue<x,vector<x>,greater<x>> #define all(x) (x).begin(),(x).end() #define CST(x) cout<<fixed<<setprecision(x) #define vtpl(x,y,z) vector<tuple<x,y,z>> #define rev(x) reverse(x); using ll=long long; using vl=vector<ll>; using vvl=vector<vector<ll>>; using pl=pair<ll,ll>; using vpl=vector<pl>; using vvpl=vector<vpl>; const ll MOD=1000000007; const ll MOD9=998244353; const int inf=1e9+10; const ll INF=4e18; const ll dy[9]={0,1,-1,0,1,1,-1,-1,0}; const ll dx[9]={1,0,0,-1,1,-1,1,-1,0}; template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; } template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; } int main(){ string s,t;cin >> s >> t; ll a=0,b=0; rep(i,s.size()){ a<<=1; if(s[i]=='1')a+=1; } rep(i,t.size()){ b<<=1; if(t[i]=='1')b+=1; } cout << (a^b) << endl; }