#include <bits/stdc++.h>
using namespace std;

bool prime(int x) {
    for(int i = 2; i * i <= x; ++i)
        if(x % i == 0)
            return false;
    return true;
}

bool special(int x) {
    vector<int> digits;

    while(x) {
        digits.push_back(x % 10);
        x /= 10;
    }

    int sz = digits.size();
    reverse(digits.begin(), digits.end());

    for(int mask = 0; mask < (1 << sz); ++mask) {
        int now = 0;
        for(int i = 0; i < sz; ++i)
            if((1 << i) & mask)
                now = now * 10 + digits[i];
        if(not prime(now))
            return false;
    }

    return true;
}

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

    vector<int> digits = {2, 3, 5, 7};
    
    int ans = 0;

    for(int mask = 0; mask < (1 << 4); ++mask) {
        vector<int> tmp;
        for(int i = 0; i < 4; ++i)
            if((1 << i) & mask)
                tmp.push_back(digits[i]);

        do {
            int val = 0;
            for(int i = 0; i < int(tmp.size()); ++i)
                val = val * 10 + tmp[i];
            if(special(val) and val >= a and val <= b) {
                ans++;
            }
        } while(next_permutation(tmp.begin(), tmp.end()));
    }

    cout << ans << "\n";
}