#include <cstdio>
#define Nmax 1000010

using namespace std;

int n,i,j,fr[Nmax];
long long nr=1LL;

int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);

    scanf("%d", &n);

    for (i=1;i<=n;++i) fr[i]=i-1;
    for (i=2;i<=n;++i)
     {
         nr+=1LL*fr[i];
         for (j=2*i;j<=n;j+=i) fr[j]-=fr[i];
     }

    printf("%lld\n", 2*nr-1);


    return 0;
}