#include <bits/stdc++.h>
#define ll long long
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int a[1000001];
int i,j,n;
ll sol;
int main()
{
    fin>>n;
    for(i=1;i<=n;i++)
        for(j=2*i;j<=n;j+=i)a[j]++;
    sol=n;
    for(i=2;i<=n;i++)
        sol+=n-(n/i)-a[i]+1;
    fout<<sol<<"\n";
    return 0;
}