#include<cstdio>
using namespace std;
int v[1000005];
int i,j,n,x,y;
long long nr=0;
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    for(i=1;i<=n;i++) v[i]=i-1;
    for(i=2;i<=n;i++)
    {
        x=v[i];
        for(j=i*2;j<=n;j+=i)
            {
                v[j]=v[j]-x;
            }
        nr+=x;
    }
    printf("%lld",2*nr+1);
}