#include <bits/stdc++.h>
using namespace std;

vector<long> primes={2L,3L,5L,7L,11L,13L,17L,19L,23L,29L,31L,37L,41L,43L,47L,53L,59L,61L,67L,71L,73L,79L,83L,89L,97L};

int main(void){
	long n;
	cin >> n;
	for(int i=0;i<(int)primes.size();i++){
	    n/=primes[i];
	    if(n==0){
	        cout << i << endl;
	        break;
	    }
	}
	return 0;
}