#include <stdio.h>
#include <functional>
#include <bitset>
#include <math.h>
#include <time.h>
#include <stdlib.h>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <sstream>
#include <queue>
#include <string.h>
#include <numeric>
using namespace std;

 typedef vector<int> vi;
 typedef vector<vi> vvi;
 typedef pair<int,int> ii;
 typedef long long ll;
 #define sz(a) int((a).size())
 #define pb push_back
 #define all(c) (c).begin(),(c).end()
 #define tr(c,i) for(typeof((c).begin() i = (c).begin(); i != (c).end(); i++)
 #define present(c,x) ((c).find(x) != (c).end())
 #define cpresent(c,x) (find(all(c),x) != (c).end())

vi primes;
bool prime[1000010];
void sieve (ll N)
{
	memset(prime,1,sizeof prime);
	prime[0] = prime[1] = 1;
	for (ll i=2 ; i<=N ; i++)
	{
		if (!prime[i]) continue;
		for (ll j = i*i ; j<=N ; j+=i)
		{
			prime[j] = 0;
		}
		primes.pb(i);
	}
}

ll calc (ll N)
{
	ll ret=0;
	for (int i=0 ; i<sz(primes) ; i++)
	{
		if (primes[i] > N) break;
		ll q = primes[i];
		while (q <= N)
		{
			ret += floor(((N-q)*1.0)/q) + 1;
			q*=primes[i];
		}
	}
	return ret;
}

int main ()
{
	//freopen("*.in","r",stdin);
	//freopen("*.out","w",stdout);

	sieve(1000000);
	int N;
	while (cin >> N)
	{
		cout << calc(N) << endl;
	}
}