#include<fstream>
using namespace std;
int a[1000000];
int main()
{long nrf=0, n, r, b, i, j;

ifstream f("fractii.in");
ofstream h("fractii.out");
f>>n;

for (i=2; i<=n; i++)
	a[i]=i-1;
for (i=2; i<=n; i++)
{nrf=nrf+a[i];
j=2*i;
do
{a[j]=a[j]-a[i];
j=j+i;}
while(j<=n);
}
nrf=nrf*2=1;
	

h<<nrf<<'\n';


	
	f.close();
	h.close();
	return 0;
	}