#include<stdio.h>
#include<math.h>
int main()
{
	long n,i,j,p,x,k,f=0;
	unsigned long e;
	int v;
	freopen("fractii.in", "r", stdin);
	freopen("fractii.out", "w", stdout);
	scanf("%ld", &n);
	for(i=2; i<=n; i++)
	{
		x=i;
		p=0;
		v=0;
		while(x%2==0)
		{
			p++;
			x=x/2;
			v=1;
		}
		if(p>0)
			e=(long unsigned int)pow(2,p-1);
		else
			e=1;
		for(j=3; (x!=1)&&(j<=sqrt(i)); j+=2)
		{
			if(x%j==0)
			{
				v=1;
				p=0;
				while(x%j==0)
				{
					p++;
					x=x/j;
				}
				e=e*(j-1)*(long unsigned int)pow(j,p-1);
			}
		}
		if(v==0)
			e=i-1;
		else
		{
			for(k=j+2; x!=1; k+=2)
			{
				if(x%k==0)
				{
					p=0;
					while(x%k==0)
					{
						p++;
						x=x/k;
					}
					e=e*(k-1)*(long unsigned int)pow(k,p-1);
				}
			}
		}
		f=f+2*e;
	}
	f=f+1;
	printf("%ld\n", f);
	return 0;
}