#include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     int tt, c = 0;     cin >> tt;     while (tt) {       int n = tt;       set<int> data;       while (n % 2 == 0) {         data.insert(2);         n = n / 2;       }       for (int i = 3; i <= sqrt(n); i = i + 2) {         while (n % i == 0) {           data.insert(i);           n = n / i;         }       }       if (n > 2) data.insert(n);       if (data.size() == 2) {         c++;       }       tt--;     }     cout << c << endl;     cerr <<  Time :   << (float)clock() / CLOCKS_PER_SEC <<   s  << endl;     return 0;   }   