#include<iostream>

 #include<string>

 #include<algorithm>

 #include<cstdio>

 #include<cstring>

 #include<cstdlib>

 #include<cmath>

 using namespace std;

 typedef long long s64;

 const int ONE = 1e7+;

 int T;

 int n,m;

 bool isp[ONE];

 int prime[],p_num;

 int miu[ONE],sum_miu[ONE];

 s64 Ans;

 int get()

 {

         int res=,Q=;  char c;

         while( (c=getchar())< || c>)

         if(c=='-')Q=-;

         if(Q) res=c-;

         while((c=getchar())>= && c<=)

         res=res*+c-;

         return res*Q;

 }

 void Getmiu(int MaxN)

 {

         miu[] = ;

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

         {

             if(!isp[i])

                 isp[i] = , prime[++p_num] = i, miu[i] = -;

             for(int j=; j<=p_num, i*prime[j]<=MaxN; j++)

             {

                 isp[i * prime[j]] = ;

                 if(i % prime[j] == )

                 {

                     miu[i * prime[j]] = ;

                     break;

                 }

                 miu[i * prime[j]] = -miu[i];

             }

             miu[i] += miu[i-];

         }

 }

 int main()

 {

         n=get();

         Getmiu(n);

         for(int d=; d<=p_num; d++)

         {

             if(prime[d] > n) break;

             int N = n/prime[d];

             for(int i=,j=; i<=N; i=j+)

             {

                 j = min(N, N/(N/i));

                 Ans += (s64)(N/i) * (N/i) * (miu[j] - miu[i-]);

             }

         }

         printf("%lld",Ans);

 }