#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <fstream>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>
#include <iterator>

typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;

ll gcd(ll a, ll b) {
    if (a < b)swap(a, b);
    if (b == 0)return a;
    return gcd(b, a % b);
}
int lcm(int a, int b) {
    return a * b / gcd(a, b);
}


string ans,s = "";
void tec(string s,ll i) {
    if (i == 1) {
        ans = s;
        return;
    }
    
    i--;
    if (i % 2 == 0) tec(s+'A',i/2); 
    if (i % 3 == 0)  tec(s + 'B', i/3);  
}



int main()
{

    int Q;
    Q = 1;
    //cin >> Q;   

    while (Q--) {
        ll n;
        cin >> n;
        unsigned long long x = 1;
        ll ans = 1;
        if (n < 2)ans = 0;
        x *= 2;
        for (ll i = 3; x <= n; i += 2) {
            bool f = 1;
            for (ll j = 3; j * j <= i; j += 2) {
                if (i % j == 0) {
                    f = 0; break;
                }
            }
            if (f) {
                x *= i; 
                if (x <= n)ans++;
                else break;
            }
        }
        
        cout << ans;
    }
        return 0;
}