#include<stdio.h>
int ciur[1000010];
int main()
{
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	int rez,i,n,j;
	scanf("%d",&n);
	for(i=1;i<=n;i++)
		ciur[i]=i-1;
	for(i=1;i<=n;i++)
		for(j=i+i;j<=n;j+=i)
			ciur[j]-=ciur[i];
	rez=0;
	for(i=1;i<=n;i++)
		rez+=ciur[i];
	rez=rez<<1;
	rez++;
	printf("%d\n",rez);
	return 0;
}