#include <cstdio>

using namespace std;
long long s;
int x[1000004],i,j,n;
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);

    scanf("%d",&n);
    for(i=1;i<=n;++i) x[i]=i-1;

    for(i=2;i<=n;++i)
    for(j=2;i*j<=n;++j)
    x[i*j]-=x[i];

    s=0LL;
    for(i=2;i<=n;++i) s+=x[i];
    s*=2;++s;

    printf("%lld\n",s);

    return 0;
}