#include<stdio.h>   
int main()   
{   
	freopen("fractii.in","r",stdin);   
	freopen("fractii.out","w",stdout);   
	long long N,j,phi[1000001],i,s;   
	scanf("%lld",&N);   
	for(i=1;i<=N;++i) phi[i]=i-1;   
	for(i=2;i<=N;++i) for(j=2*i;j<=N;j+=i) phi[j]-=phi[i];
	s=0;
	for(i=2;i<=N;i++) s=s+phi[i];   
	printf("%lld",(2*s)+1);   
	return 0;   
}