#include <bits/stdc++.h>
// #include <atcoder/all>
// using namespace atcoder;
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define rrep(i,n) for(int i=int(n-1);i>=int(0);--i)
#define fore(i,a) for(auto &i:a)
#define all(x) x.begin(),x.end() 
#define sz(x) ((int)(x).size())
#define bp(x) (__builtin_popcount((long long)(x)))
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define V vector
#define P pair<int,int>
#define TP tuple<int,int,int>
#define F first
#define S second
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
using ll = long long;
using ld = long double;
using namespace std;
const int INF = 1001001001;
const ll INFL = 1001001001001001001;
const int MAX = 2e6+1;

int main() {
    int a,b;cin>>a>>b;
    int c=a;
    c|=b;
    int d=a;
    d&=b;
    cout<<c-d<<endl;
    

}