#include  <iostream>
#include  <fstream>
 using namespace std;
ifstream f ("fractii.in ");
ofstream g ("fractii.out ");
int main ()
{
long long suma=0,nr=1;
int n, v [1000001];
f>>n;
for (int i=1;i <=n;++i)
v[i]=i-1;
for (int i=2;i <=n;++i)
for (int j=2*i;j <=n;j+=i)
v[j]-=v[i];
for (int j=1;j <=n;++j)
suma+=v[j];
suma=suma*2;suma++;
g <<suma;
return 0; 
}