#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,m,n) for(int i=m; i<n; ++i)
#define repl(i,m,n) for(ll i=m; i<n; ++i)

int main(){
    ll N;
    cin >> N;

    vector<int> prime_list;
    for(int i = 2; i < 100 && prime_list.size() < 15; ++i){
        bool is_prime = true;
        for(int j = 2; j*j <= i; ++j){
            if(i % j == 0){
                is_prime = false;
                break;
            }
        }
        if(is_prime) prime_list.push_back(i);
    }

    vector<ll> vec;
    vec.push_back(2LL);
    rep(i, 1, 15){
        vec.push_back(ll(vec.back()*prime_list[i]));
    }

    auto it = lower_bound(vec.begin(), vec.end(), N);
    cout << it - vec.begin() << endl;

    return 0;
}