#include <stdio.h>

int n,ciur[9][1010];
long nr = 0;

int main ()
{
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%d",&n);
	
	nr = n * 2 - 1;
	
	for (int i = 2;i <= n; i++)
	{
		int nr_max = n - i;
		if (!ciur[0][i])
			for (int j = i + i;j <= n;j = j + i)
				{
					nr_max --;
					{
						ciur[0][j]++;
						ciur[ciur[0][j]][j] = i;
					}
			}
		/*if (!ciur[0][i])
			for (int j = i + i;j <= n;j = j + i)
				nr_max--;
		*/
		for (int k = 1;k <= ciur[0][i]; k++)
			for (int j = i + ciur[k][i];j <= n;j = j + ciur[k][i])
				nr_max --;
		
		nr += nr_max * 2;
	}
	
	
	printf("%ld",nr);
	
}