bit : bit array i and j are starting and ending index INCLUSIVE
static long bit_q ( int i , int j ) { long sum = 0 ; while ( j > 0 ) { sum += bit [ j ] ; j -= ( j & ( j * - 1 ) ) ; } i -- ; while ( i > 0 ) { sum -= bit [ i ] ; i -= ( i & ( i * - 1 ) ) ; } return sum ; }