#include<bits/stdc++.h>
#define FOR(x,a,b) for (int x=a;x<=b;x++)
#define FOD(x,a,b) for (int x=a;x>=b;x--)
#define pub push_back
#define pob pop_back
#define ii  pair<int,int>
#define pll pair<long long, long long>
#define F first
#define S second
#define fast {ios_base::sync_with_stdio(false);cin.tie(NULL);}
typedef unsigned long long int ull;
typedef long long ll;
const long N=1e6 + 5;
const int mod = 1e9 +7;
using namespace std;
ll n,res=0;
bool kt[N+1];
void them(){
    FOR(i,0,N) {
        kt[i] = true;
    }
    kt[0] = false;
    kt[1] = false;
    for(int i = 2; i * i <= N; ++i) {
         if(kt[i] == true) {
             for(int j = i * i; j <= N; j += i)
                 kt[j] = false;
        }
    }
}
void solve(){
    them();
    cin >> n;
    n=sqrt(sqrt(n));
    for(int i=1;i<=n;i++)
    {
        if (kt[i]) res++;
    }
    cout << res;
}
int main(){
    fast;
     freopen("beaunum.inp","r",stdin);
     freopen("beaunum.out","w",stdout);
    solve();
    return 0;
}