#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max()/32*15+208;

class UnionFind {
    int n;
    vector<int> uni;
    int forest_size;
public:
    explicit UnionFind(int n) : n(n), uni(static_cast<u32>(n), -1), forest_size(n) {};

    int root(int a){
        if (uni[a] < 0) return a;
        else return (uni[a] = root(uni[a]));
    }

    bool unite(int a, int b) {
        a = root(a);
        b = root(b);
        if(a == b) return false;
        if(uni[a] > uni[b]) swap(a, b);
        uni[a] += uni[b];
        uni[b] = a;
        forest_size--;
        return true;
    }
    int size(){ return forest_size; }
    int size(int i){ return -uni[root(i)]; }
    bool same(int a, int b) { return root(a) == root(b); }
};

int main() {
    int l, r;
    cin >> l >> r;
    vector<int> v(r+1, 1);
    UnionFind uf(r-l+1);
    int ans = 0;
    for (int i = l; i <= r; ++i) {
        for (int j = i+i; j <= r; j += i) {
            uf.unite(i-l, j-l);
        }
    }
    cout << uf.size()-1 << "\n";
    return 0;
}