#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<bitset>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<deque>
#include<list>
#include<iomanip>
#include<cmath>
#include<cstring>
#include<functional>
#include<cstdio>
#include<cstdlib>
#include<numeric>
//#include<atcoder/all>
using namespace std;
//using namespace atcoder;

#define repr(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define rep(i, n) repr(i, 0, n)
#define INF 2e9
#define MOD 1000000007
//#define MOD 998244353
#define LINF (long long)4e18
#define jck 3.141592
#define PI acos(-1.0)

const double EPS = 1e-10;

using ll = long long;
using Pi = pair<int,int>;
using Pl = pair<ll,ll>;

bool is_square(int a){
    int b = sqrt(a);
    return b*b == a;
}


int main(){
    int n; cin >> n;
    vector<int> square_sum(n+1);
    repr(i,1,n+1){
        if(is_square(i)) square_sum[i] = square_sum[i-1]+1;
        else square_sum[i] = square_sum[i-1];
    }

    ll ans = 0;
    vector<bool> prime(n+1,true);
    vector<ll> to_prod(n+1,1);
    for(int i = 2; i <= n; i++){
        if(!prime[i]) continue;
        for(int j = i; j <= n; j+=i){
            prime[j] = false;
            int cnt = 0;
            int k = j;
            while(k%i==0){
                k /= i;
                cnt++;
            }
            if(cnt%2==1) to_prod[j] *= i;
        }
    }
    repr(i,1,n+1){
        if(to_prod[i] <= n){
            ans += square_sum[n/to_prod[i]];
        }
    }
    cout << ans << endl;

}