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

#define int long long
#define rep(i,l,r) for(int i=(int)(l);i<(int)(r);i++)
#define all(x) (x).begin(),(x).end()
template<class T>bool chmax(T &a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,T b){if(a>b){a=b;return 1;}return 0;}

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;

const int inf = 1LL<<60;
const int mod = 1e9 + 7;
const double eps = 1e-9;

/*{
  }*/

signed main(){
  int n;
  cin >> n;

  vi p(n+1, 1);
  p[0] = p[1] = 0;
  rep(i, 2, n+1){
    rep(j, 2, n/i+1){
      p[i*j] = 0;
    }
  }

  vi prime;
  rep(i, 0, n+1) if(p[i]) prime.emplace_back(i);

  int ans = 0;
  for(int i : prime){
    int x = 2+i;
    int y = sqrt(x);
    if(y*y == x and p[y]) ans += i != 2 ? 2 : 1;
  }

  cout << ans << endl;

  return 0;
}