#include <bits/stdc++.h>

using namespace std;

using lli = int64_t;
using pii = pair<int, int>;
using vint = vector<int>;
using triple = pair<int, pii>;
using C = int;
using P = complex<C>;

const int MX = 505;
const int MOD = 1e9 + 7;

lli n, m;
lli res = 0;

bool is_prime(lli x) {
    if (x % 2 == 0 && x != 2)
        return false;

    for (lli i = 3; i <= sqrt(x + 1); i += 2) {
        if (x % i == 0)
            return false;
    }

    return true;
}

lli Pow(lli b, lli p) {
    if (p == 0)
        return 1;

    lli a = Pow(b, p / 2);

    if (p % 2 == 1) {
        return a * a * b;
    }

    return a * a;
}

void solution(lli x, lli d = 1) {
    if (x > m)
        return;

    if (!is_prime(x))
        return;

    if (x >= n) {
        res++;
    }

    lli ld = x / Pow(10, d - 1);

    if (ld == 2 || ld == 5)
        return;

    if (ld == 3) {
        solution(7 * Pow(10, d) + x, d + 1);
    } else {
        solution(3 * Pow(10, d) + x, d + 1);
    }

    solution(2 * Pow(10, d) + x, d + 1);
    solution(5 * Pow(10, d) + x, d + 1);
}

void solve() {
    cin >> n >> m;

    solution(2);
    solution(3);
    solution(5);
    solution(7);

    cout << res;
}

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

    int t = 1;
    // cin >> t;

    while (t--) {
        solve();
        cout << '\n';
    }

    return 0;
}