#include<iostream>
#include<stdio.h>
long long n,a[1000009],nr;
FILE *f,*g;
void functii()
{
	int i,j;
	for(i=1;i<=n;i++)
		a[i]=i-1;
	for(i=2;i<=n;i++)
	{
			for(j=i+i;j<=n;j+=i)
				a[j]-=a[i];
		nr+=a[i];
	}
	nr=nr*2+1;
	fprintf(g,"%ld",nr);
}
int main()
{   nr=0;
	f=fopen("fractii.in","r");
	g=fopen("fractii.out","w");
	fscanf(f,"%ld",&n);
	functii();
	return 0;
}