Problem:
Partition

Quick sort is based on the Divide-and-conquer approach. In QuickSort(A, p, r), first, a procedure Partition(A, p, r) divides an array A[p..r] into two subarrays A[p..q-1] and A[q+1..r] such that each element of A[p..q-1] is less than or equal to A[q], which is, inturn, less than or equal to each element of A[q+1..r]. It also computes the index q.

In the conquer processes, the two subarrays A[p..q-1] and A[q+1..r] are sorted by recursive calls of QuickSort(A, p, q-1) and QuickSort(A, q+1, r).

Your task is to read a sequence A and perform the Partition based on the following pseudocode:

Partition(A, p, r)
1 x = A[r]
2 i = p-1
3 for j = p to r-1
4 do if A[j] <= x
5 then i = i+1
6 exchange A[i] and A[j]
7 exchange A[i+1] and A[r]
8 return i+1

Note that, in this algorithm, Partition always selects an element A[r] as a pivot element around which to partition the array A[p..r].

Input

The first line of the input includes an integer n, the number of elements in the sequence A.

In the second line, Ai (i = 1,2,...,n), elements of the sequence are given separated by space characters.

Output

Print the sorted sequence. Two contiguous elements of the sequence should be separated by a space character. The element which is selected as the pivot of the partition should be indicated by [  ].

Constraints

1 ≤ n ≤ 100,000

0 ≤ Ai ≤ 100,000

Sample Input 1

12
13 19 9 5 12 8 7 4 21 2 6 11

Sample Output 1

9 5 8 7 4 2 6 [11] 21 13 19 12

Solution in Python (judge verdict: Accepted)

#!/usr/bin/python
#_*_coding:utf-8_*_


def partition(array, p, r):
    x = array[r]
    i = p - 1
    for j in range(p, r):
        if array[j] <= x:
            i = i + 1
            v = array[i]
            array[i] = array[j]
            array[j] = v
    va = array[i + 1]
    array[i + 1] = array[r]
    array[r] = va

    return i + 1, array


def main():
    n = raw_input()
    num = raw_input()
    array = num.strip().split(" ")
    array = map(int, array)
    index, new_array = partition(array, 0, len(array) - 1)
    new_array = map(str, new_array)
    new_array[index] = "[" + new_array[index] + "]"
    print " ".join(new_array)

if __name__ == '__main__':
    main()