#include <bits/stdc++.h>
int main() {
  int n, d, i, j;
  int c = 0;
  int e = 0;
  int x[10000];
  scanf("%d", &n);
  x[0] = 1;
  for (j = 1; j <= n - 1; j++) {
    x[j] += 1;
  }
  for (i = 0; i <= n - 1; i++) {
    for (d = 1; d <= i + 1; d++) {
      if (x[i] % d == 0) {
        e++;
      }
    }
    if (e == 2) {
      c++;
      e = 0;
    }
  }
  printf("%d\n", c);
  return 0;
}
