#include <iostream>
#include <cstdio>

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

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+a[i]*2;
     printf("%d",s);
     return 0;
     
}