#include<stdio.h>
unsigned long v[1000001];
int main()
{
  unsigned long long nr=0;
  unsigned  i,j,n;
 FILE *f=fopen("fractii.in","r");
 FILE *g=fopen("fractii.out","w");
 fscanf(f,"%u",&n);
    for (i=2;i<=n;i++)
        v[i]=i-1;
    for (i=2;i<=n;i++)
        for (j=2*i;j<=n;j=j+i)
            v[j]=v[j]-v[i];
    for (i=2;i<=n;i++)
        nr=nr+v[i]*2;
 fprintf(g,"%llu",nr+1);
}