#include<bits/stdc++.h> using namespace std; typedef long long ll; signed main(){ ios::sync_with_stdio(false); cin.tie(0); ll n; cin>>n; vector<int> p(n+1,1); p[0]=0,p[1]=0; vector<int> prime; for(int i=2;i<=n;i++){ if(p[i]){ for(int j=i+i;j<=n;j+=i){ p[j]=0; } prime.push_back(i); } } ll ans=0; for(int q=0;q<prime.size();q++){ if(prime[q]*prime[q]>2*n) break; for(int r=0;r<prime.size();r++){ ll t=prime[q]*prime[q]-prime[r]; if(t>0 && t<=n && p[t]) ans++; } } cout<<ans<<endl; }