#include <iostream>
#include <vector>
using namespace std;

struct SieveEratos{
  vector<bool> t;
  SieveEratos(int n):t(n+1,true){
    t[0] = t[1] = false;
    for(int i = 2; n >= i; i++){
      if(t[i]){
        for(int j = i+i; n >= j; j+=i){
          t[j] = false;
        }
      }
    }
  }
  bool operator[](int x){return t[x];}
};



int main(){
  long long n;cin>>n;
  SieveEratos A(n+1);
  int ans = 0;
  for(long long i = 0; n >= i; i++){
    if(!A[i])continue;
    for(long long j = 0; n >= j*j; j++){
      if(!A[j] || j*j-i < 0)continue;
      //cout << i << " " << j << endl;
      if(A[j*j-i])ans++;
    }
  }
  cout << ans << endl;
}