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