#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef modint1000000007 mint;
typedef pair<ll,ll> P;
#define rep(i,a,b) for(ll i=a;i<b;i++)
#define rrep(i,a,b) for(ll i=a;i>=b;i--)
const ll inf=1e18;
int main(void){
    cin.tie(0);
    ios::sync_with_stdio(0);
    int a,b;
    cin>>a>>b;
    int ans=(a|b)-(a&b);
    cout<<ans<<endl;
}