#include<iostream>
#include<fstream>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");


int main(){
	long long n,i,j,a=0,v[1000001];
	f>>n;
for(i=2;i<=n;i++) v[i]=i-1;
for(i=2;i<=n;i++){
	a=a+v[i];
	for(j=2*i;j<=n;j=j+i) v[j]=v[j]-v[i];}

	g<<a*2+1;
return 0;	
}