#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
template<typename T> using vc = vector<T>;
template<typename T> using vv = vc<vc<T>>;
using vl = vc<ll>;
using vvl = vc<vc<ll>>;
using vul = vc<ull>;
using vs = vc<string>;
#define rep(i,n) for(ll i=0;i<(n);i++)
#define Rep(i,n) for(ll i=n-1;i>=0;i--)
//#define rep(i,n) for(ull i=0;i<(n);i++)
#define nall(x) x.begin(),x.end()
#define pb push_back
#define pob pop_back
#define YES cout<<"Yes"<<endl
#define NO cout<<"No"<<endl
#define YN {cout<<"Yes"<<endl;}else{cout<<"No"<<endl;}
#define M1 cout<<"-1"<<endl
const long long INF = (1LL<<62)-(1LL<<31)-1;
#define denl endl
#define edln endl
#define ednl endl
//vl dx = {1,-1,0,0};vl dy = {0,0,1,-1};
//vl dx={0,0,1,1,1,-1,-1,-1};vl dy={1,-1,0,1,-1,0,1,-1};
int main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	ll a,b;
	cin >> a >> b;
	cout << (a^b) << endl;
}