#include <bits/stdc++.h>

 using namespace std;

 int n,m,mu[],f[],p[];bool o[];

 int main()

 {

     scanf("%d",&n);

     mu[]=;

     for(int i=;i<=n;i++)

     {

         if(!o[i]) p[++m]=i,mu[i]=-,f[i]=;

         for(int j=;j<=m;j++)

         if((long long)p[j]*i<=(long long)n)

         {

             o[p[j]*i]=;

             if(i%p[j]==) f[p[j]*i]=mu[i];

             else f[p[j]*i]=mu[i]-f[i];

             if(i%p[j]==) break;

             mu[i*p[j]]=-mu[i];

         }

         else break;

     }

     long long ret=;

     for(int i=;i<=n;i++)

         ret+=(long long)(n/i)*(n/i)*f[i];

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

     return ;

 }