#include <iostream>
#include <cstdio>

using namespace std;
int n,i,j,a[100000000];
long long s;

int main()
{
     freopen("fractii.in","r",stdin);
     freopen("fractii.out","w",stdout);
     scanf("%d",&n);
     for(i=1;i<=n;i++)
                      a[i]=i-1;
     for(i=2;i<=n;i++)
                      for(j=2;i*j<=n;j++)
                          a[i*j]=a[i*j]-a[i];
     s=1;                                                    
     for(i=1;i<=n;i++)
                      s=s+2*a[i];
     printf("%d",s);
     return 0;
     
}