#include <bits/stdc++.h>
using namespace std;

int main() {
  int a, b;
cin >> a >> b;
int c, d;
if (a < b) {
c = a;
d = b;
a = d;
b = c;
}
if (3 * b >= a) {
cout << (a + b) % 2 << endl;
}
else {
cout << 2 * b << endl;
}
}