#include<stdio.h>
int k,n,i,j,a[1000002];
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    k=0;
    for(i=2;i<=n;i++)
    {
        a[i]=i-1;
    }
    for(i=2;i<=n;i++)
    {
        k+=a[i];
        for(j=i+i;j<=n;j+=i)
            a[j]-=a[i];
    }
    printf("%d",2*k+1);
    return 0;
}