#include<iostream>

 #include<cstdio>

 #include<cstring>

 #include<algorithm>

 #include<cmath>

 #include<queue>

 using namespace std;

 #define LL long long

 const int maxn=;

 LL n;

 LL phi[maxn]={};

 LL pri[maxn/]={},tot=;

 bool v[maxn]={};

 void get_phi(int m){

     phi[]=;

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

         if(!v[i]){pri[++tot]=i;phi[i]=i-;}

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

             int w=pri[j]*i;v[w]=;

             if(i%pri[j]==){phi[w]=phi[i]*pri[j];break;}

             phi[w]=phi[i]*(pri[j]-);

         }

     }

     //for(int i=1;i<=10;++i)cout<<phi[i]<<endl;

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

         phi[i]+=phi[i-];

     }

 }

 LL solve(LL m){

     if(m<=maxn-)return phi[m];

     LL ans=m*(m+)/;

     for(LL i=,las;i<=m;i=las+){

         las=m/(m/i);

         ans-=(LL)(las-i+)*solve(m/i);

     }

     return ans;

 }

 int main(){

     get_phi(maxn-);

     scanf("%lld",&n);

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

     return ;

 }