#include<stdio.h>

#define M 1000005
int v[M];

int main()
{
	FILE* f1=fopen("fractii.in","r");
	FILE* f2=fopen("fractii.out","w");
	long n;
	fscanf(f1,"%ld",&n);
	for(int i=2;i<=n;i++)
		v[i]=i-1;
	for(int i=2;i<=n;i++)
		for(int j=2*i;j<=n;j+=i)
			v[j]=v[j]-v[i];
	long long s=0;
	for(int i=2;i<=n;i++)
		s+=(long long)v[i];
	fprintf(f2,"%Ld",2*s+1);
	return 0;
}