#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const ll M = 2000000000;

int main() {
	ll A, B; cin >> A >> B;
	ll ans = max(0LL, abs(A-B)-1);
	if (A > B) {
		ans += M-A;
	}
	else {
		ans += A-1;
	}
	cout << ans << endl;
}