//#include <fstream>
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

//ifstream cin("x.in"); ofstream cout("x.out");

int v[ 10 ] = {
 0, 2, 23, 5, 53, 3, 37, 7, 73
};

int main() {
    int a, b;
    cin >> a >> b;

    int ans = 0;
    for (int i = 1; i <= 8; ++ i) {
        if (a <= v[ i ] && v[ i ] <= b) {
            ++ ans;
        }
    }
    cout << ans << "\n";

    return 0;
}