#include<bits/stdc++.h>
using namespace std;
int solve(int l, int r, int x) {
	if (x == 0) return 0;
	if (l == r) return 0;
	if (r - l + 1 == x) return 0;
	int mid = l + r - 1 >> 1;
	if (mid - l == r - mid - 1) return 1 + solve(l, mid, x / 2) + solve(mid + 1, r, ceil(x * 1.0 / 2));
	else if (mid - l > r - mid - 1) return 1 + solve(l, mid, ceil(x * 1.0 / 2)) + solve(mid + 1, r, x / 2);
	return 1 + solve(l, mid, x / 2) + solve(mid + 1, r, ceil(x * 1.0 / 2));
}
int main()
{
	int n, m;
	cin >> n >> m;
	cout << solve(1, n, m);
	return 0;
}