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

int N, P;
bool sosuu[1000010];

int main() {
	
	cin >> N >> P;
	int ans = N - 1;
	for (int i = 0; i <= N; i++) sosuu[i] = false;
	
	for (int i = 2; i <= N; i++) {
		if (sosuu[i] == false) {
			int n = i * 2;
			while (n <= N) {
				sosuu[n] = true;
				n += i;
			}
			if (i * 2 > N) ans -= 1;
		}
	}
	
	if ((sosuu[P] == false) and P * 2 > N) cout << 1;
	else cout << ans << endl;
}