#include <fstream>

using namespace std;
ifstream f ("fractii.in");
ofstream g ("fractii.out");
const int MaxN = 1000001;
int n, a[MaxN], j, i;
long long sum=0;
int main()
{
    f >> n ;
    for(i = 2; i<=n; i++)
        a[i] = i-1;
    for(i=1; i<=n; i++)
        for(j=2*i; j<=n; j+=i)
        a[j] -=a[i];
   for(i=2; i<=n; i++)
        sum +=a[i];

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