#include <cstdio>

#define file_in "fractii.in"
#define file_out "fractii.out"

int N,i,j,v[1010001],ans;

int main(){
	
	freopen(file_in,"r",stdin);
	freopen(file_out,"w",stdout);
	
	scanf("%d", &N);
	
	for (i=1;i<=N;++i) v[i]=i-1;
	for (i=2;i<=N;++i)
		 for (j=i+i;j<=N;j+=i)
			  v[j]-=v[i];
	ans=0;
	for (i=2;i<=N;++i)	
		 ans+=v[i];
	
	printf("%d\n", 2*ans+1);
	
	return 0;
	
}