#include<bits/stdc++.h>
#define REP1(i,n,m) for(int i=n;i<=m;i++)
#define REP2(i,n,m) for(int i=n;i>=m;i--)
using namespace std;
void YN(bool f){if(f){cout<<"YES"<<endl;}else{cout<<"NO"<<endl;}}
int main(){
	int a,b;
	cin>>a>>b;
	cout<<(a|b)-(a&b)<<endl;
	
	
	
}