#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}


Int isprime(Int x){
  if(x<=1) return 0;
  for(Int i=2;i*i<=x;i++)
    if(x%i==0) return 0;
  return 1;
}

//INSERT ABOVE HERE
signed main(){
  Int n;
  cin>>n;
  vector<Int> ps;
  for(Int i=2;i<=n;i++)
    if(isprime(i)) ps.emplace_back(i);

  const Int MAX = 1e6+10;
  vector<Int> qs;
  Int ans=0;
  for(Int r:ps){
    if(r>MAX/r+1) break;
    for(Int p:ps){
      if(binary_search(ps.begin(),ps.end(),r*r-p)) ans++;
    }
  }
  cout<<ans<<endl;
  return 0;
}