# include <stdio.h>
int main (){
	int n,nr=1,p,q,ok,d,min;
   freopen("fractii.in","r",stdin);
   freopen("fractii.out","w",stdout);
	scanf("%d",&n);
	for(p=1;p<n;p++)
   	for(q=p+1;q<=n;q++){
      	ok=1;
         if (p<q) min=p;
             else min=q;
         for(d=2;d<=min && ok;d++)
         	if(p%d==0 && q%d==0) ok=0;
         if(ok)
           {nr++; nr++;}
		}
   printf("%d ",nr);
	printf("\n");
	return 0;
}