dziala lol

#include <iostream>
#include <queue>

std::queue<long long> q;
long long num[4] = {1, 3, 7, 9};

bool check(long long x) {
    if (x == 1 || x == 0)
        return false;
    for (long long i = 2; i * i <= x; i++) {
        if (x % i == 0)
            return false;
    }
    return true;
}

int main() {
    long long min, max;
    scanf("%lld%lld", &min, &max);
    q.push(2);
    q.push(3);
    q.push(5);
    q.push(7);
    long long ile = 0;
    while (!q.empty()) {
        if (min <= q.front() && q.front() <= max)
            ile++;
        for (auto it : num) {
            if (q.front() * 10 + it <= max && check(q.front() * 10 + it))
                q.push(q.front() * 10 + it);
        }
        q.pop();
    }
    printf("%lld", ile);
    return 0;
}