#include <bits/stdc++.h>
#include <vector>

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;

#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(x) begin (x), end(x)
#define sz(x) (int) (x).size()
#define rep(i,a,b) for (int i = (a); i < (b); i++)

mt19937 rng(random_device{}());

using i128 = __int128;
using ull = unsigned long long;
using u128 = __uint128_t;

ull modMul(ull a, ull b, ull mod) { return (u128)a * b % mod;}

bool checkPrime(ll p, ll a) {
	ll k = p - 1, d = 1;
	while (~k & 1) k >>= 1;
	for (ll e = k; e; e >>= 1) {
		if (e & 1) d = i128(d) * a % p;
		a = i128(a) * a % p;
	}
	if (d == 1 || d == p - 1) return true;
	while ((k <<= 1) < p - 1) {
		d = i128(d) * d % p;
		if (d == p - 1) return true;
	}

	return false;
} // d5cf5e

bool isPrime(ll p) {
	if (p == 1) return false;
	for (int i: {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37}){
		if (p == i) return true;
		if (!checkPrime(p, i)) return false;
	}
	return true;
} // a137c8


int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);

	unsigned long long n;
	unsigned long long num = 1;
	cin >> n;
	ll index = 2;
	ll quant = 0;

	while(num <= n){
		if(isPrime(index)){
			num = num * index;
			if(num <= n){
				quant++;
			}
		}
		index++;
	}

	cout << quant << endl;

	return 0;
}