#include<fstream>
using namespace std;
int main()
{long long N,j,phi[900001],i,s;
ifstream fin("fractii.in");
ofstream fout("fractii.out");

fin>>N;

for (i = 1; i <= N; ++i)
    phi[i] = i-1;

for (i = 2; i <= N; ++i)
    for (j = 2*i; j <= N; j += i)
	phi[j] -= phi[i];;
s=0;
for(i=2;i<=N;i++)
  s=s+phi[i];
fout<<(2*s)+1;
fin.close();
fout.close();
return 0;
}