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

int main()
{
    vector<long long> prime = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47};
    long long N;
    cin >> N;
    long long now = 1;
    int ans = 0;
    for (int i = 0; i < prime.size(); i++)
    {
        if (now * prime[i] <= N)
        {
            ans++;
            now *= prime[i];
        }
        else
        {
            break;
        }
    }
    cout << ans;
}