#include<iostream>
#include<cstring>
#include<fstream>
using namespace std;

int main()
{
	int n,count[1000001],curent=0,mark[1000001];
	ifstream in("fractii.in");
	ofstream out("fractii.out");

	in>>n;
	count[1]=n;
	for(int i=2;i<=n;i++)
		count[i]=1;
	memset(mark,0,sizeof(mark));
	for(int i=2;i<=n;i++)
	{
		int marked=0,j;
		if(mark[i]==1)
			marked++;
		curent=1;
		for(j=i+i;j<=n;j+=i)
		{
			count[j]+=curent;
			++curent;
			if(mark[j]==1)
			{
				count[j]-=marked;
				++marked;
			}
		}
		j-=i;
		if(mark[j]==1)
			marked=1;
		else
			marked=0;
		curent=1;
		j-=i;
		for(;j>=0;j-=i)
		{
			count[j]+=curent;
			++curent;
			if(mark[j]==1)
			{
				count[j]-=marked;
				++marked;
			}
		}
		for(j=i+i;j<=n;j+=i)
			mark[j]=1;
		mark[i]=1;
	}
	long long int sum=0;
	sum+=count[1];
	for(int i=2;i<=n;i++)
		sum+=n-count[i];
	out<<sum<<endl;
	in.close();
	out.close();
}