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

#define ll long long
#define ull unsigned long long
#define nl '\n'
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define rall(s)  s.rbegin(), s.rend()
#define getline(s) getline(cin>>ws,s)
#define ceill(n, m) (((n) / (m)) + ((n) % (m) ? 1 : 0))
#define pi  3.141592653589793

/*
███╗░░██╗███████╗░██████╗░███╗░░░███╗
████╗░██║██╔════╝██╔════╝░████╗░████║
██╔██╗██║█████╗░░██║░░██╗░██╔████╔██║
██║╚████║██╔══╝░░██║░░╚██╗██║╚██╔╝██║
██║░╚███║███████╗╚██████╔╝██║░╚═╝░██║
╚═╝░░╚══╝╚══════╝░╚═════╝░╚═╝░░░░░╚═╝

*/

void Fast_IO(){
ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
// freopen("filename.in", "r", stdin);
#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
#endif
}


vector<ll>prime(5000);
void sieve(){
    for(int i=2; i<=3000; i++){
        if(!prime[i]){
            for(int j = 2*i; j<=3000; j+=i) prime[j]++;
        }
    }
}


void solve(){
    sieve();
    ll n,res =0; cin>>n;

    for(int i=2; i<=n; i++){
        if(prime[i]==2) res++;
    }
    cout<<res<<nl;



}

int main(){
    Fast_IO();
int t =1;
//cin>>t;
while(t--){
solve();
}
return 0;
}