#include <fstream>
using namespace std;
ifstream in ("fractii.in");
ofstream out ("fractii.out");

long long n, i, j, cnt = 0, v [ 1000000 ];

int main()
{
	in>>n;

	for ( i = 2; i <= n; ++i )
	{
		v [ i ] += i - 1;
		for ( j = i + i; j <= n; j += i )
			v [ j ] -= v [ i ];
		cnt += v [ i ];
	}
	
	out<<2*cnt + 1;
	return 0;
}