#include <bits/stdc++.h>
using namespace std;
 
#define fi first
#define se second
#define pb push_back
using vi = vector <int>;
using ll = long long;
using pii = pair <int, int>;
const ll mod = 998244353;
//~ const ll mod = 1e9 + 7;
ll qpow(ll a, ll b, ll m = mod) { ll r = 1, t = a;
	for(; b; b /= 2) { if(b & 1) r = r * t % m; t = t * t % m; } return r; }

const int N = 2e5 + 11;
int p[N];
int find(int x) {
	if(p[x] == x) return x;
	return p[x] = find(p[x]);
}

int main() {
	ios :: sync_with_stdio(false);
	
	int l, r; cin >> l >> r;
	
	iota(p, p + r + 1, 0);
	int ans = r - l;
	
	for(int i = l; i <= r; i ++)
		for(int j = i; j <= r; j += i) {
			int u = find(i), v = find(j);
			if(u != v) {
				ans --;
				p[v] = u;
			}
		}
	cout << ans << '\n';
}