#include<stdio.h>
#define N 1000000
int phi[N];
int main () {
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	int i,j,n;
	long long s=0;
	scanf("%d",&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];
	for(i=2;i<=n;++i)
		s+=phi[i];
	printf("%lld\n",2*s+1);
	return 0;
}