#include <stdio.h>#include <string.h>#include <queue>#include <math.h>#include <vector>#include <algorithm>using namespace std ;typedef long long LL ;#define clr( a , x ) memset ( a , x , sizeof a )const int MAXN = 1000005 ;LL phi[MAXN] ;int pri[MAXN] , cnt ;void preprocess () {cnt = 0 ;for ( int i = 2 ; i < MAXN ; ++ i ) {phi[i] = i ;}for ( int i = 2 ; i < MAXN ; ++ i ) {if ( phi[i] == i ) {phi[i] = i - 1 ;pri[cnt ++] = i ;}for ( int j = 0 ; j < cnt && i * pri[j] < MAXN ; ++ j ) {if ( i % pri[j] == 0 ) {phi[i * pri[j]] = phi[i] * pri[j] ;break ;}phi[i * pri[j]] = phi[i] * ( pri[j] - 1 ) ;}phi[i] += phi[i - 1] ;}}int main () {int n ;preprocess () ;while ( ~scanf ( "%d" , &n ) && n ) printf ( "%I64dn" , phi[n] ) ;return 0 ;}
