//minamoto

 #include<cstdio>

 #define ll long long

 const int N=1e7+;

 int p[],n,m;short mu[N];bool vis[N];ll sum[N],ans;

 void init(int n){

     mu[]=;

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

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

         for(int j=;j<=m&&p[j]*i<=n;++j){

             vis[i*p[j]]=;

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

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

         }

     }

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

     for(int i=;i*p[j]<=n;++i)

     sum[i*p[j]]+=mu[i];

     for(int i=;i<=n;++i) sum[i]+=sum[i-];

 }

 int main(){

     scanf("%d",&n),init(n);

     for(int l=,r;l<=n;l=r+){

         r=n/(n/l);

         ans+=(sum[r]-sum[l-])*(n/l)*(n/l);

     }

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

     return ;

 }