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

#define int long long
const int mxn = 2e5 + 5;
int p[mxn];

int find (int i) {
    if (p[i] < 0) return i;
    return p[i] = p[i] == i ? i : find(p[i]);
}

bool get (int a, int b) {
    a = find(a), b = find(b);
    return a == b;
}

void unite (int a, int b) {
    a = find(a), b = find(b);
    if (a == b) return;
    p[a] += p[b];
    p[b] = a;
}

void solve(){
    int l, r;
    cin >> l >> r;
    for (int i = l; i <= r; i++) p[i] = -1;
    for (int i = l; i < r; i++) {
        if (find(i) != i) continue;
        for (int j = 2 * i; j <= r; j += i) {
            unite(i, j);
        }
    }
    int ans = 0;
    for (int i = l; i <= r; i++) {
        if (find(i) == i) ans++;
    }
    cout << ans - 1 << "\n";
}

signed main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    
    int T = 1;
    // cin >> T;
    while(T--) solve();

    return 0;
}