#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2")
#include <bits/stdc++.h>
#define INF 1000000001LL
#define LNF 1000000000000000001LL
#define MOD 1000000007LL
#define MAX 502
#define long long long
#define all(x) x.begin(),x.end()
using namespace std;

class UnionFind
{
public:
    vector<int> parent;
    vector<int> cnt;
    void init(int size)
    {
        parent.resize(size);
        cnt.resize(size);
        for(int i = 0; i<size; i++)
        {
            parent[i] = i;
            cnt[i] = 1;
        }
    }
    int find(int x)
    {
        if(parent[x] == x)
            return x;
        return parent[x] = find(parent[x]);
    }
    void merge(int x, int y)
    {
        x = find(x);
        y = find(y);
        if(x == y)
            return;
        if(x < y)
        {
            parent[y] = x;
            cnt[x]+=cnt[y];
        }
        else
        {
            parent[x] = y;
            cnt[y]+=cnt[x];
        }
    }
    bool isUnion(int x, int y)
    {
        x = find(x);
        y = find(y);
        if(x == y)
            return true;
        return false;
    }
};

int main()
{
	ios_base::sync_with_stdio(0); 
    cin.tie(0);

    int l,r;
    cin >> l >> r;

    UnionFind uf;
    uf.init(r+1);

    for(int i= l; i<=r; i++)
    {
        for(int j = i+i; j<=r; j+=i)
            uf.merge(i,j);
    }
    int res = 0;
    for(int i= l; i<=r; i++)
    {
        if(uf.find(i) == i)
            res++;
    }
    cout << res-1 << endl;
    return 0;
}