#include<stdio.h>   
  
long n,i,j;   
long long a[1000001];   
long long b;   
  
int main()   
{   
    freopen("fractii.in","r",stdin);   
    freopen("fractii.out","w",stdout);   
    b=1;   
    scanf("%ld",&n);   
    for(i=2;i<=n;i++)   
      {   
      a[i-2]=(long long)(a[i-2]+i-1);   
      for(j=2*i;j<=n;j+=i)   
            {   
            a[j-2]=(long long)(a[j-2]-a[i-2]);   
            }   
      b=(long long)(b+2*a[i-2]);   
      }   
     printf("%lld\n",b);   
     return 0;   
}