/* -*- coding: utf-8 -*-
 *
 * 843.cc:  No.843 Triple Primes - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 500000;

/* typedef */

/* global variables */

bool primes[MAX_N + 1];
int pnums[MAX_N];

/* subroutines */

int gen_primes(int maxp, int pnums[]) {
  memset(primes, true, sizeof(primes));
  primes[0] = primes[1] = false;

  int p, pn = 0;
  for (p = 2; p * p <= maxp; p++)
    if (primes[p]) {
      pnums[pn++] = p;
      for (int q = p * p; q <= maxp; q += p) primes[q] = false;
    }
  for (; p <= maxp; p++)
    if (primes[p]) pnums[pn++] = p;
  return pn;
}

/* main */

int main() {
  int n;
  scanf("%d", &n);

  int pn = gen_primes(n, pnums);
  //printf("pn=%d\n", pn);

  int cnt = 0;
  for (int i = 0; i < pn; i++) {
    int &pi = pnums[i];
    int maxr2 = pi + n;

    for (int j = 0, r2; (r2 = pnums[j] * pnums[j]) <= maxr2; j++)
      if (r2 > pi && primes[r2 - pi]) cnt++;
  }

  printf("%d\n", cnt);
  return 0;
}