#include <bits/stdc++.h>
#include <atcoder/all>
typedef long long int ll;
typedef long long int ull;
#define MP make_pair
using namespace std;
using namespace atcoder;
typedef pair<ll, ll> P;
const ll MOD = 998244353;
// const ll MOD = 1000000007;
using mint = modint998244353;
// using mint = modint1000000007;
const double pi = 3.1415926536;
const int MAX = 2000005;
long long fac[MAX], finv[MAX], inv[MAX];
template<typename T> using min_priority_queue = priority_queue<T, vector<T>, greater<T>>;
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}
// 二項係数計算
long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
ll gcd(ll x, ll y) {
   if (y == 0) return x;
   else if (y > x) {
       return gcd (y, x); 
   }
   else return gcd(x % y, y);
}
ll lcm(ll x, ll y) {
   return x / gcd(x, y) * y;
}
ll my_sqrt(ll x) {
    ll m = 0;
    ll M = 3000000001;
    while (M - m > 1) {
        ll now = (M + m) / 2;
        if (now * now <= x) {
            m = now;
        }
        else {
            M = now;
        }
    }
    return m;
}
ll keta(ll n, ll hou) {
    ll ret = 0;
    while (n) {
        n /= hou;
        ret++;
    }
    return ret;
}
ll ceil(ll n, ll m) {
    // n > 0, m > 0
    ll ret = n / m;
    if (n % m) ret++;
    return ret;
}

ll pow_ll(ll x, ll n) {
    if (n == 0) return 1;
    if (n % 2) {
        return pow_ll(x, n - 1) * x;
    }
    else {
        ll tmp = pow_ll(x, n / 2);
        return tmp * tmp;
    }
}
#define MAXP 1000000
bool is_prime[MAXP]; // 1スタート
ll primelist[MAXP]; //0スタート
//範囲の素数もカウント
int setp() {
    memset(primelist, 0, sizeof(primelist));
    memset(is_prime, true, sizeof(is_prime));
    is_prime[1] = false;
    int k = 2;
    while (k < MAXP) {
        if (is_prime[k]) {
            for (int l = k; l <= MAXP / k; l++) {
                is_prime[k * l] = false;
            }
        }
        k++;
    }
    int count = 0;
    for (int i = 1; i < MAXP; i++) {
        if (is_prime[i]) {
            primelist[count] = i;
            count++;
        }
    }
    return count;
}

vector<ll> compress(vector<ll> v) {
    // [3 5 5 6 1 1 10 1] -> [1 2 2 3 0 0 4 0] 
    vector<ll> u = v;
    sort(u.begin(), u.end());
    u.erase(unique(u.begin(),u.end()),u.end());
    map<ll, ll> mp;
    for (int i = 0; i < u.size(); i++) {
        mp[u[i]] = i;
    }
    for (int i = 0; i < v.size(); i++) {
        v[i] = mp[v[i]];
    }
    return v;
}

ll nums[1000001];
bool sqfr[1000001];
int main() {
    ll l, r;
    cin >> l >> r;
    ll pnum = setp();
    for (ll i = 0; i < r - l + 1; i++) {
        nums[i] = l + i;
        sqfr[i] = true;
    }
    for (int i = 0; i < pnum; i++) {
        ll start = primelist[i] * ceil(l, primelist[i]);
        for (ll j = start; j <= r; j += primelist[i]) {
            int cnt = 0;
            while (nums[j - l] % primelist[i] == 0) {
                nums[j - l] /= primelist[i];
                cnt++;
            }
            // cout << primelist[i] << ' ' <<  j << ' ' << cnt << endl;
            if (cnt >= 2) sqfr[j - l] = false;
        }
    }
    for (ll i = 0; i < r - l + 1; i++) {
        if ((sqfr[i]) && (nums[i] > 1)) {
            ll x = my_sqrt(l + i);
            // cout << i << endl;
            if (x * x == l + i) sqfr[i] = false;
        }
    }
    int cnt = 0;
    for (int i = 0; i < r - l + 1; i++) {
        if (sqfr[i]) {
            // cout << l + i << endl;
            cnt++;
        }
    }
    cout << cnt << endl;
    return 0;
}