#include<bits/stdc++.h>
using namespace std;
int main() {
  vector<int> A = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47};
  long long N;
  cin >> N;
  int M = A.size();
  vector<long long> B(M, 1LL);
  for (int i = 0; i < M; i++) {
    for (int j = 0; j <= i; j++) {
      B[i] *= A[j];
    }
  }
  int i = 0;
  B[0] = 0;
  while (B[i] <= N && i < M) {
    i++;
  }
  cout << i << endl;
}