#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
using ll = long long;
using ull = unsigned long long; 
using pii =  pair<int, int>;
using pll =  pair<long long, long long>;
#define rep(i, n) for(int i = 0; i < (n); ++i)
#define all(x) (x).begin(),(x).end()
constexpr char ln =  '\n';
constexpr long long MOD = 1000000007LL;
//constexpr long long MOD = 998244353LL;
template<class T, class U> inline bool chmax(T &a, U b) { if (a < b) { a = b; return true;} return false; }
template<class T, class U> inline bool chmin(T &a, U b) { if (a > b) { a = b; return true;} return false; }
////////////////////////////////////////////////////////////////////////////////////////////////////////////

struct UnionFind {
    vector<int> node;

    UnionFind() = default;
    UnionFind(int x) {init(x);}

    void init(int x) {
        node.assign(x,-1);
    }

    bool merge(int x, int y) {
        x = root(x); y = root(y);
        if (x == y) return false;
        if (node[x] > node[y]) swap(x,y);
        node[x] += node[y];
        node[y] = x;
        return true; 
    }

    bool same(int x, int y) {
        return root(x) == root(y);
    }

    int root(int x) {
        if (node[x] < 0) return x;
        return node[x] = root(node[x]);
    }

    int size(int x) {
        return -node[root(x)];
    }
};

int main() {
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int L,R; cin >> L >> R;
    UnionFind uf(R-L+1);
    for (int i = L; i <= R; i++) {
        for (int j = 2; j*i <= R; j++) {
            uf.merge(i-L,j*i-L);
        }
    }
    set<int> dic;
    rep(i,R-L+1) {
        dic.emplace(uf.root(i));
    }
    
    cout << dic.size()-1 << ln;
}