#include<iostream>
#include<fstream>
long phi[1000000];
using namespace std;
int main()
{long long i,n,c=0,j;
ifstream f("fractii.in");
ofstream g("fractii.out");
f>>n;
for (i = 1; i <= n; i++)
    phi[i] = i-1;
for (i = 2; i <= n; i++)
    for (j = 2*i; j <= n; j=j+ i)
        phi[j]= phi[j] - phi[i];
for (i=1;i<=n;i++)
	c=c+phi[i];
cout<<c*2+1;
g<<c*2+1;
g.close();
f.close();
return 0;
}