#include <bits/stdc++.h>
#include <atcoder/modint>
#include <atcoder/dsu>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint;
using edge = pair<ll, pair<int, int>>;
int main() {
	vector<edge> ED;
	int L, R;cin >> L >> R;
	int N = R - L + 1;
	for (int l = L;l < R;l++) {
		ED.push_back({1, {l - L, l + 1 - L}});
		int now = 2 * l;
		while (now <= R) {
			ED.push_back({0LL, {l - L, now - L}});
			now += l;
		}
	}
	sort(ED.begin(), ED.end());
	dsu uf(N);
	ll ans = 0;
	for (auto ed : ED) {
		int a = ed.second.first;int b = ed.second.second;
		if (!uf.same(a, b)) {
			uf.merge(a, b);
			ans += ed.first;
		}
	}
	cout << ans << endl;
}