#include <bits/stdc++.h>

using namespace std;

bool isPrime(int n) {
  if (n <= 1) {
    return false;
  }

  for (int x = 2; x * x <= n; x++) {
    if (n % x == 0) {
      return false;
    }
  }

  return true;
}

bool check(string &s) {
  int n = (int) s.size();

  for (int mask = 1; mask < (1 << n); mask++) {
    int val = 0;
    for (int i = 0; i < n; i++) {
      if (mask & (1 << i)) {
        val = 10 * val + s[i] - '0';
      }
    }

    if (!isPrime(val)) {
      return false;
    }
  }

  return true;
}

int main() {
	// assert(freopen("subnumbers.in", "r", stdin));
	// assert(freopen("subnumbers.out", "w", stdout));
	cin.sync_with_stdio(false);

	int a, b;
  cin >> a >> b;

  b = min(b, 10000);

  int ans = 0;
  string s;
  for (int x = a; x <= b; x++) {
    stringstream ss;
    ss << x;
    ss >> s;

    bool ok = true;
    for (int i = 0; i < (int) s.size() && ok; i++) {
      if (s[i] != '2' && s[i] != '3' && s[i] != '5' && s[i] != '7') {
        ok = false;
      }
    }

    if (ok && check(s)) {
      ans++;
    }
  }

  cout << ans << endl;

	return 0;
}