#include <bits/stdc++.h>
#define FASTIO
using namespace std;

using ll = long long;
using Vi = vector<int>;
using Vl = vector<ll>;
using Pii = pair<int, int>;
using Pll = pair<ll, ll>;

constexpr int I_INF = numeric_limits<int>::max();
constexpr ll L_INF = numeric_limits<ll>::max();

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

class UnionFind {
    using i64 = std::int64_t;

private:
    std::vector<i64> par;
    std::vector<i64> sz;

public:
    UnionFind(i64 N) : par(N), sz(N, 1) {
        for (i64 i = 0; i < N; ++i) par[i] = i;
    }
    i64 root(i64 x) {
        return par[x] == x ? x : par[x] = root(par[x]);
    }
    bool same(i64 x, i64 y) {
        return root(x) == root(y);
    }
    void unite(i64 x, i64 y) {
        x = root(x);
        y = root(y);
        if (x == y) return;
        if (sz[x] < sz[y]) std::swap(x, y);
        par[y] = x;
        sz[x] += sz[y];
    }
    i64 size(i64 x) {
        return sz[root(x)];
    }
    void reset(i64 N) {
        par.resize(N);
        for (i64 i = 0; i < N; ++i) par[i] = i;
        sz.assign(N, 1);
    }
};

void solve() {
    ll L, R;
    cin >> L >> R;

    UnionFind uf(R - L + 1);
    for (ll i = L; i <= R; i++) {
        for (ll j = 2 * i; j <= R; j += i) {
            uf.unite(i - L, j - L);
        }
    }

    unordered_set<ll> st;
    for (ll i = 0; i < R - L + 1; i++) {
        st.emplace(uf.root(i));
    }

    cout << (ll)st.size() - 1 << endl;
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

int main() {
#ifdef FASTIO
    cin.tie(0), cout.tie(0);
    ios::sync_with_stdio(false);
#endif
#ifdef FILEINPUT
    ifstream ifs("./in_out/input.txt");
    cin.rdbuf(ifs.rdbuf());
#endif
#ifdef FILEOUTPUT
    ofstream ofs("./in_out/output.txt");
    cout.rdbuf(ofs.rdbuf());
#endif
    solve();
    cout << flush;
    return 0;
}