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

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl
#define p_yes() p("Yes")
#define p_no() p("No")

const ll mod = 1e9 + 7;
const ll inf = 1e18;

const int N_MAX = 1e6 + 10;
bool is_prime[N_MAX];

// エラトステネスのふるい
void Eratosthenes(){
    FOR(i, 0, N_MAX){
        is_prime[i] = true;
    }
    is_prime[0] = false;
    is_prime[1] = false;
    for(ll i=2; i*i<=N_MAX; i++){
        if(is_prime[i]){
            int p = i;
            int step_p = p;
            // それの倍数を消していく
            while(p < N_MAX){
                p += step_p;
                if(p<N_MAX){
                    is_prime[p] = 0;
                }
            }
        }
    }
}

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

    // input
    ll N;
    cin >> N;

    Eratosthenes();

    ll limit = min(N+1, (ll)sqrt(500000)+100);

    ll count = 0;
    FOR(r, 2, limit){
        if(!is_prime[r]) continue;
        FOR(p, 2, N+1){
            if(!is_prime[p]) continue;

            ll q = r*r - p;
            if(q<=1) continue;
            if(q>N) continue;
            if(is_prime[q]){
                // cout << "pqr " << p << ' ' << q << ' ' << r << endl; 
                count++;
            }
        }
    }
    p(count);
    
    return 0;
}