#include <iostream>
using namespace std;
int main() {
int a,b;
cin >> a >>b;
int c = a^b;
cout << c << endl;
return 0;
}
I2luY2x1ZGUgPGlvc3RyZWFtPgp1c2luZyBuYW1lc3BhY2Ugc3RkOwoKaW50IG1haW4oKSB7CiAgICBpbnQgYSxiOwogICAgY2luID4+IGEgPj5iOwogICAgaW50IGMgPSBhXmI7CiAgICBjb3V0IDw8IGMgPDwgZW5kbDsKICAgIHJldHVybiAwOwp9