#include<cstdio>

#include<cstring>

#include<queue>

#include<cstdlib>

#include<algorithm>

#include<vector>

#include<cmath>

using namespace std;

typedef long long LL;

const int N=1e7+;

const int INF=0x3f3f3f3f;

bool vis[N];

int prime[N],mu[N],cnt;

void getmu()

{

    mu[] = ;

    for(int i=; i<=N-; i++)

    {

        if(!vis[i])

        {

            prime[++cnt] = i;

            mu[i] = -;

        }

        for(int j=; j<=cnt&&i*prime[j]<=N-; j++)

        {

            vis[i*prime[j]] = ;

            if(i%prime[j]) mu[i*prime[j]] = -mu[i];

            else

            {

                mu[i*prime[j]] = ;

                break;

            }

        }

    }

}

int main(){

    getmu();

    for(int i=;i<=N-;++i)mu[i]+=mu[i-];

    int n;

    scanf("%d",&n);

    LL ans=;

    for(int i=;i<=cnt&&prime[i]<=n;++i){

        int l=n/prime[i];

      for(int k=,j;k<=l;k=j+){

         j=l/(l/k);

        ans+=1ll*(mu[j]-mu[k-])*(l/k)*(l/k);

      }

    }

    printf("%lld\n",ans);

    return ;

}