#include <bits/stdc++.h>

#define el '\n'
#define ll long long
#define ld long double

#define Beevo ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

using namespace std;

const int N = 2e6 + 5;

bool prime[N];
vector<string> primes;

void sieve() {
    memset(prime, 1, sizeof prime);

    for (int i = 2; i * i < N; i++) {
        if (prime[i]) {
            for (int j = i + i; j < N; j += i)
                prime[j] = 0;
        }
    }

    for (int i = 2; i < N; i++) {
        if (prime[i])
            primes.push_back(to_string(i));
    }
}

bool solve(string &s, string &t) {
    for (int i = 0; i + t.size() - 1 < s.size(); i++) {
        if (s.substr(i, t.size()) == t)
            return 1;
    }

    return 0;
}

void testCase() {
    sieve();

    int l, h;
    string s;
    cin >> l >> h >> s;

    int cnt = 0;
    for (int i = l - 1; i < h; i++)
        cnt += solve(primes[i], s);

    cout << cnt;
}

signed main() {
    Beevo

    int T = 1;
//    cin >> T;

    while (T--)
        testCase();

    return 0;
}