#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;
}