#include <cstdio>

using namespace std;
long long nr;
int phi[ 2000005],i,j,cate,n;
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    for (int i = 1; i <=n; ++i)
    phi[i] = i-1;
     for (int i = 2; i <=n; ++i)
    for (int j = 2*i; j <= n; j += i)
        phi[j] -= phi[i];
     for(i=1;i<=n;i++)
       nr+=phi[i];

       printf("%lld",2*nr+1);


    return 0;
}