#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int INF = 1<<30;
const long long INFLL = 1LL<<60;
const int MOD = 998244353;

ll n, m;
vector<ll> primes;
vector<bool> judge(1000, true);

void make_primes(){
    judge[0] = false;
    judge[1] = false;
    
    for (int i=2; i < 1000; i++){
        if (!judge[i]) continue;
        primes.push_back(i);
        for (int j=i; j < 1000; j+=i) judge[j] = false;
    }
}

int main() {
    cin >> n;
    
    m = 1;
    make_primes();
    for (int i=0; i < (int)primes.size(); i++){
        if (primes[i] == 53){
            cout << 15 << endl;
            break;
        }
        m *= primes[i];
        //cout << primes[i] << ":" << m << endl;
        if (m > n || m < 0){
            cout << i << endl;
            break;
        }
    }
    return 0;
}