// includes {{{
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<tuple>
#include<cmath>
#include<random>
#include<cassert>
#include<bitset>
#include<cstdlib>
// #include<deque>
// #include<multiset>
// #include<cstring>
// #include<bits/stdc++.h>
// }}}
using namespace std;
using ll = long long;

// O(N log log N)
/// --- primes {{{ ///
#include <vector>
vector< int > primes(int n) {
  vector< int > res;
  for(int i = 2; i <= n; ++i) {
    bool isp = 1;
    for(int p : res) {
      if((ll) p * p > i) break;
      if(i % p == 0) {
        isp = 0;
        break;
      }
    }
    if(isp) res.emplace_back(i);
  }
  return res;
}
/// }}}--- ///

bool isprime[1123456];

int main() {
  std::ios::sync_with_stdio(false), std::cin.tie(0);
  int n;
  cin >> n;

  auto ps = primes(n);
  for(int p : ps) isprime[p] = 1;
  int ans = 0;

  for(int ri = 0; ri < ps.size() && ps[ri] * ps[ri] <= n * 2; ri++) {
    for(int pi = 0; pi < ps.size(); pi++) {
      int q = ps[ri] * ps[ri] - ps[pi];
      if(0 <= q && q <= n && isprime[q]) ans++;
    }
  }



  cout << ans << endl;
  return 0;
}