#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
#include <deque>
#include <queue>
#include <array>
#include <set>
#include <map>
#include <cmath>
#include <algorithm>
#include <numeric>
#include <cassert>
#include <utility>
#include <tuple>
#include <functional>
#include <bitset>
#include <cstdint>

using namespace std;
using i64 = int64_t;
using i32 = int32_t;
template<class T, class U> void init_n(vector<T>& v, size_t n, U x) 
{ v = vector<T>(n, x); }
template<class T> void init_n(vector<T>& v, size_t n) { init_n(v, n, T()); }
template<class T> void read_n(vector<T>& v, size_t n, size_t o = 0) 
{ v = vector<T>(n+o); for (size_t i=o; i<n+o; ++i) cin >> v[i]; }
template<class T> void read_n(T a[], size_t n, size_t o = 0)
{ for (size_t i=o; i<n+o; ++i) cin >> a[i]; }
template<class T> T gabs(const T& x) { return max(x, -x); }
#define abs gabs

int main() {
  i64 n;
  cin >> n;
  
  vector<bool> sv(n + 1);
  vector<i64> ps;
  for (i64 i = 2; i <= n; ++i) {
    if (!sv[i]) {
      for (i64 j = 2 * i; j <= n; j += i) sv[j] = true;
      ps.push_back(i);
    }
  }
  
  i64 ans = 0;
  for (i64 x : ps) {
    for (i64 y : ps) {
      i64 z = y * y - x;
      if (z > n) break;
      if (2 <= z && z <= n && !sv[z]) ++ans;
    }
  }
  cout << ans << endl;
  return 0;
}