#include<stdio.h>
int main () {
	long n,i,j,x[1000001],k,nr=0;
	freopen ("fractii.in","r",stdin);
	freopen ("fractii.out","w",stdout);
	scanf("%ld",&n);
	for (i=2; i<=n; i++) 
	{
		x[i]=i-1;
	}
	for (i=2; i<=n; i++)       
    {	
		for (j=2*i; j<=n; j=j+i)       
        {
			x[j]=x[j]-x[i];       
			nr+=x[i];
		}
    }
	k=2*nr+1;
	printf ("%ld",k);
	return 0;
}