#include<fstream>
using namespace std;
int n, rasp[1000002], i, j;
long long raspFinal;

int main()
{ 
    
	ifstream f("fractii.in");
	ofstream g("fractii.out");
	
	f>>n;
	for(i=2;i<=n;i++)
{   
    rasp[i]=i-1;
}

for(i=2;i<=n;i++)
{  raspFinal+=rasp[i];

        for(j=i+i;j<=n;j+=i)
        {   rasp[j]-=rasp[i];}
        }
        
g<<2*raspFinal+1;


}