#include<stdio.h>
#define NMAX 1000005
long long int k,N,primi[10],SOL[NMAX];
void citire()
{
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%lld",&N);
}
void descompunere(long long int x)
{
	long long int i;k = 0;
	for(i = 2;  x!=1; i++)
	{
		if(x%i==0)
		{
			for(;x%i==0;x/=i);
			primi[++k] = i;
		}
	}
}
void euler()
{
	SOL[1] = 1, SOL[2] = 1;
	for(long long int i = 3 ; i <= N; i++)
	{
		descompunere(i);
		double e = i*1.0;
		for(int j = 1 ; j <= k ; j++)
			e*=1-(1.0/primi[j]);
		SOL[i] = (long long int)e;
	}

}
void construire()
{
	for(int i = 2 ; i <= N; i++)
		SOL[i] = SOL[i-1] + (2*SOL[i]);
}
int main()
{
	citire();
	euler();
	construire();
	printf("%lld",SOL[N]);
	return 0;
}