#include<fstream>
using namespace std;
int n,a[1000001],i,j;
long long nr;
ifstream f("fractii.in");
ofstream g("fractii.out");

int main() {
f>>n;
for (i=2;i<=n;++i)
    a[i]=i-1;
for (i=2;2*i<=n;++i)
    for (j=2*i;
     j<=n; j+=i)
      a[j]-=a[i];
for (i=2; i<=n;++i)
 nr+=a[i];
g<<2*nr+1;
return 0;
}