#include<cstdio>
int main()
{
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	int n,i,j,s=0,nr;
	int v[100]; 
	scanf("%d", &n);
	for(i=1;i<=n;i++)
		v[i]=i;
	for(i=1;i<=n/2;i++)
		for(j=i*2;j<=n;j=j+i)
				v[j]=v[j]-v[i];
	for(i=2;i<=n;i++)
		s=s+v[i];
	//printf("%d",s);
	nr=s*2+1;
	printf("%d",nr);
	
	return 0;
}