#include<stdio.h>
int k,n,i,j,a[1000001];
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];
    k=1;
    for(i=1;i<=n;i++)
        k+=2*a[i];
    printf("%d",k);
    return 0;
}