#include <iostream> #include <set> using namespace std; bool is_perfect(int n) { if(n < 6) return false; set<int> factor; for(int i = 1; i <= n / 2; ++i) { if(n % i == 0) factor.insert(i); } int sum = 0; for(const int& n: factor) { sum += n; } return sum == n; } int main() { int n; cin >> n; int ans = 0; for(int i = 6; i <= n; ++i) { if(is_perfect(i)) ++ans; } cout << ans << endl; return 0; }