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

int main() {
    vector<bool> prime(1000000, true);
    for (int i = 2; i < 1000000; i++) {
        if (!prime[i]) {
            continue;
        }
        for (int j = i * 2; j < 1000000; j += i) {
            prime[j] = false;
        }
    }
    vector<long long> p;
    for (int i = 2; i < 1000000; i++) {
        if (prime[i]) {
            p.push_back((long long)i);
        }
    }
    long long n;
    cin >> n;
    long long cur = 1LL;
    for (int i = 0; i < (int)p.size(); i++) {
        if (cur <= n / p[i]) {
            cur *= p[i];
        } else {
            cout << i << endl;
            return 0;
        }
    }
}