#include<stdio.h>
#include<math.h>
long n,x,d,nrd;
long long nr=1;
FILE *f,*g;
int main()
{
	f=fopen("fractii.in","r");
	fscanf(f,"%ld",&n);fclose(f);
	for(x=2;x<=n;x++)
	{nrd=0;
	for(d=2;d<=sqrt(x);d++)if(x%d==0)nrd+=2;
	if(sqrt(x)==(int)(sqrt(x)))nrd--;
	nr+=2*(x-1-nrd);
	}
	g=fopen("fractii.out","w");
	fprintf(g,"%lld",nr);
	return 0;
}