Bzoj 2190[sdoi2008] Honor Guard

Description

As a sports Commissioner, C June is responsible for the training of the honor guard. 　　  　　Guard of Honor is composed of students of N * N of the square, in order to ensure that the procession uniform, c June will follow the guard of Honor's left rear, according to the number of students in the line of sight to determine whether the team is neat (such as). Now, C-June wants you to tell him the number of students you can see when the team is neat.

Input

A total of a number n.

Output

A total of a number, that is, c June should see the number of students.

Sample Input4

Sample Output9


HINT

"Data size and conventions" for 100% of data, 1≤n≤40000

The ... Find Phi, calculate

1#include <cstdio>2 Const intmaxn=40010;3 BOOLPD[MAXN];4 intPhi[maxn],prime[maxn],top,n,ans;5 voidES () {6      for(intI=2; i<n;i++){7         if(!Pd[i]) {8prime[++top]=i;9phi[i]=i-1;Ten         } One          for(intj=1; j<=top&&prime[j]*i<=n;j++){ Apd[prime[j]*i]=1; -             if(i%prime[j]==0){ -phi[prime[j]*i]=phi[i]*Prime[j]; the                  Break; -             } -phi[prime[j]*i]=phi[i]* (prime[j]-1); -         } +     }  - } +  A intMain () { atscanf"%d",&n); - ES (); -      for(intI=1; i<n;i++) phi[i]+=phi[i-1]; -ans=phi[n-1]*2+3; -printf"%d", ans); -}

Bzoj 2190[sdoi2008] Honor Guard