#include<iostream>
#include<cmath>
#include<bitset>
#include<vector>
#include<queue>
#include<cstring>
#include<map>
#include<set>
#include<iomanip>
#include<unordered_map>
#include<math.h>
#include<string>
#include <algorithm>
using namespace std;
#define ll long long
#define ld long double
#define pb push_back
#define mp make_pair
#define integ __int128
const ll MOD = 1e9 + 7;
const int N = 4e4 + 3;

int a[N];
int pr[20 * N];
vector<int> primes;
int n;


int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    srand(time(0));
    n = 4e4 + 3;
  //  freopen("/Users/mitterr/Desktop/a.out" , "w" , stdout);
    vector<char> prime (n+1, true);
    prime[0] = prime[1] = false;
    for (int i = 2; i <= n; ++i)
        if (prime[i])
        {
            primes.pb(i);
            pr[i] = 1;
            if ( i * i <= n)
            {
                for (int j=  i * i; j <= n; j += i)
                {
                    prime[j] = false;
                }
            }
        }
    for(int i = 1; i < N; i++)
    {
        int p = i;
        int cnt = 0;

        for(int j : primes)
        {
            if(j * j > p) break;
            while (p % j == 0)
            {
                p /= j;
                ++cnt;
            }
        }
        if(p > 1) ++cnt;
        a[i] = cnt;
    }
  //  cin >> p;
  //  cout << fact(p) << "\n";
    int l , r;
    cin >> l >> r;
  //  l = r = 0;
    int ans = 0;
    for(int i = l; i <= r; ++i)
    {
        int p = i;
        int cnt = 0;
        for(int j : primes)
        {
            if(j * j> p ) break;
            while (p % j == 0)
            {
                p /= j;
                ++cnt;
            }
        }
        if(p < N)
        cnt += a[p];
        else ++cnt;
        //  cout << i << " " << cnt << "\n";
        if(pr[cnt]) ++ans;
    }
    cout << ans << "\n";
//     cout << (double)clock() / CLOCKS_PER_SEC << "\n";
//    cout << ans << "\n";
}