#include<bits/stdc++.h>
using namespace std;
int a,b; 
int main(){
	cin>>a>>b;
	int c=a^b;
	cout<<c;
	


	return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int a,b,c=0;
	cin>>a>>b;
	c=a^b;
	cout<<c;
return 0;
}