#include <fstream>

using namespace std;

int s[1000001];
ifstream fi("fractii.in");
ofstream fo("fractii.out");

int main()
{
    int n;
    fi>>n;
    int i,j;
    long sum=0;
    for (i=1;i<=n;++i)
      s[i]=i-1;
    for (i=1;i<=n;++i)
        for (j=2*i;j<=n;j=j+i)
          s[j]-=s[i];
    for (i=2;i<=n;++i)
        sum+=s[i];
    fo<<2*sum+1;
}