#include <bits/stdc++.h>
using namespace std;
// #define int long long
#define rep(i, a, b) for (int i = a; i <= (b); i++)
#define drep(i, a, b) for (int i = a; i >= (b); i--)
typedef long long ll;
int n, c;
ll ccc(int x) {
	return (1ll * x * x - x % 2) / 4;
}
ll cal(int num) {
	int a = n / num, b = a + 1, cb = n % num, ca = num - cb;
	ll tot;
	if (num == 1)
		tot = 0;
	else {
		tot = n - 1;
		if (cb >= 2) {
			tot -= 2 * (b / 2);
		} else if (cb == 1) {
			tot -= b / 2 + a / 2;
		} else
			tot -= 2 * (a / 2);
	}
	// cout << "a=" << a << "\n";
	// cout << "b=" << b << "\n";
	// cout << "tot=" << tot << "\n";
	return tot + num * c + ccc(a) * ca + ccc(b) * cb;
}

signed main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	cin >> n >> c;

	// cout << "\ncal(1):\n"
	// 	 << cal(1) << "\n";
	// return 0;

	int l = 1, r = n;
	while (l + 20 < r) {
		int lm = l + (r - l) / 3, rm = r - (r - l) / 3;
		if (cal(lm) < cal(rm))
			r = rm;
		else
			l = lm;
	}
	ll ans = 1e18;
	rep(i, l, r) {
		// if (cal(i) == 11)
		// 	cout << "\n\ni=" << i << "\n\n";
		ans = min<ll>(ans, cal(i));
	}
	// cout << "\ncal(2):\n"
	// 	 << cal(2) << "\n";
	cout << ans;

	return 0;
}