#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <algorithm>
#include <set>
#include <map>
#include <bitset>
#include <cmath>
#include <functional>
#include <iomanip>
#define vll vector<ll>
#define vvvl vector<vvl>
#define vvl vector<vector<ll>>
#define VV(a, b, c, d) vector<vector<d>>(a, vector<d>(b, c))
#define VVV(a, b, c, d) vector<vvl>(a, vvl(b, vll (c, d)));
#define re(c, b) for(ll c=0;c<b;c++)
#define rep(a,b,c) for(ll a=b;a<c;a++)
#define all(obj) (obj).begin(), (obj).end()
typedef long long int ll;
typedef long double ld;
using namespace std;

void get(vll &a){re(i,a.size()) scanf("%lld",&a[i]);}
void get(vvl &a){re(i,a.size()) re(j,a[0].size()) scanf("%lld",&a[i][j]);}
void print(vll &a){re(i,a.size()) cout<<a[i]<<(i==a.size()-1?"\n":" ");}
void print(vvl &a){re(i,a.size()) re(j,a[0].size())cout<<a[i][j]<<(j==a[0].size()-1?"\n":" ");}

int main(int argc, char const *argv[]) {
  ll n;std::cin >> n;
  if(n==1){
    std::cout << 0 << '\n';
    return 0;
  }
  vector<bool> prm(n+1, 1);
  prm[1] = prm[0] = 0;
  for(ll i=2;i<=n;i++) for(ll j=i*i;j<=n;j+=i) prm[j] = 0;

  ll ans = 0;
  for(ll x=3;x<=n;x++){
    if(!prm[x]) continue;
    ll num = 2 + x;
    ll t = (ll)round(sqrt(num));
    if((t*t)==num&&prm[t]) ans+=2;
  }
  std::cout << ans + 1 << '\n';
  return 0;
}