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