#include<iostream.h>
#include<fstream.h>
ifstream f("fr.in");
ofstream g("fr.out");
int n,phi[1000001];


	
int main()
{
	int i,j,c=0;
	f>>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];
	clock_t start, stop;
	start=clock();
	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];
	for(i=1;i<=n;i++)
		c+=phi[i];
	c=2*c+1;	
	stop=clock();
		g<<c;
	g<<"\n"<<(double)(stop-start)/CLOCKS_PER_SEC;
return 0;
}