#include<bits/stdc++.h>
#define MAX 1000005

using namespace std;

int ans[MAX];

int give_res(int i)
{
    int j,res = 0;

    while(i%2==0)
    {
        i/=2;

        res++;
    }

    for(j=3; j*j<=i; j+=2)
    {
        while(i%j==0)
        {
            res++;

            i/=j;
        }
    }

    if(i>1)
        res++;

    return res;
}

void cumulative_sum()
{
    int i,res;

    for(i=2; i<=MAX; i++)
    {
        ans[i] = ans[i-1]+give_res(i);
    }
}

int main()
{
    cumulative_sum();

    int n;

    while(scanf("%d",&n)!=EOF)
    {
        printf("%d\n",ans[n]);
    }

    return 0;
}