#include <stdio.h>
long v[1000005];

int main()
{
	long long i,j,s=0,n;
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%lld",&n);
	for(i=1;i<=n;i++){
		v[i]=i-1;
	}
	for(i=2;i<=n;i++){
		for(j=2*i;j<=n;j=j+i){
			v[j]=v[j]-v[i];
		}
	}
	for(i=2;i<=n;i++){
		s=s+v[i];
	}
	printf("%lld\n", 2*s+1);
	return 0;
}