#include<cstdio>
#include<iostream>
#include<cstring>
using namespace std;
const int SIZEN=50010;
int cnt=0;
int mu[SIZEN],prime[SIZEN];
bool co[SIZEN];
void Prime(int N)
{
	mu[1]=1;
	for(int i=2;i<=N;i++)
	{
		if(!co[i]) mu[i]=-1,prime[++cnt]=i;
		for(int j=1;j<=cnt&&prime[j]*i<=N;j++)
		{
			co[i*prime[j]]=1;
			if(i%prime[j]==0)
			{
				mu[i*prime[j]]=0;
				break;
			}
			mu[i*prime[j]]=mu[i]*mu[prime[j]];
		}
	}
}
int N;
int main()
{
	freopen("sendtable.in","r",stdin);
	freopen("sendtable.out","w",stdout);
	scanf("%d",&N);
	Prime(N);
	int ans=0;
	//for(int i=1;i<=N;i++) cout<<mu[i]<<endl;
	for(int i=1;i<=N;i++) ans+=mu[i]*(N/i)*(N/i);
	printf("%d",ans);
	return 0;
}