#include<bits/stdc++.h>

using namespace std;

const int maxn = 1e6;
int nex[maxn];

int main() {
#ifdef MyTest
	freopen("Sakura.txt", "r", stdin);
#endif
	int m, n, ans = 0;
	cin >> m >> n;
	for(int i = 1; i < n; i += 2) nex[i] = i + 2;
	for(int i = 3; i < n; i = nex[i]) {
		if(i > m) ++ans;
		int no = 2, tmp = 3, pre = 1;
		while(tmp < n) {
			if(no % i == 0) nex[pre] = nex[tmp];
			else pre = tmp;
			++no, tmp = nex[tmp];
		}
	}
	cout << ans;
	return 0;	
}