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