#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using mint = atcoder::modint1000000007;

int main(){
	ll n;
	cin>>n;
	vector<ll> p={2,3,5,7,11,13,17,19,23,29,31,37,41,43,47};
	ll ans=1;
	int i=0;
	for(auto x:p){
		ans*=x;
		if(ans>n){
			cout<<i<<endl;
			return 0;
		}
		i++;
	}
	cout<<i<<endl;
}