#include <iostream>
#include <stdio.h>
#define fin "fractii.in"
#define fout "fractii.out"
using namespace std;
long a[1000002],n;

int main()
{
    freopen(fin,"r",stdin);
    freopen(fout,"w",stdout);
    long i,j;
    cin>>n;
    for(i=2;i<=n;i++)
        a[i]=i-1;
    for(i=2;i<=n;i++)
        for(j=i*2;j<=n;j+=i)
            a[j]-=a[i];
    j=0;
    for(i=2;i<=n;i++)
        j+=a[i];
    cout<<j*2+1;
    return 0;
}