#include <stdio.h>

int main () {
  long long n = 0LL;
  
  int res = 0;
  
  int ans = 0;
  long long tmp = 1LL;
  
  long long p[20] = { 2LL, 3LL, 5LL, 7LL, 11LL, 13LL, 17LL, 19LL, 23LL, 29LL, 31LL, 37LL, 41LL, 43LL, 47LL, 53LL, 59LL, 61LL, 67LL, 71LL };
  
  res = scanf("%lld", &n);
  
  while (tmp <= n/p[ans]) {
    tmp *= p[ans];
    ans++;
  }
  
  printf("%d\n", ans);
  return 0;
}