18732번 - A Permutation Problem 스페셜 저지다국어

Zenyk has a permutation of n integers from 1 to n, inclusive. His task is to sort the permutation, and he has to swap each pair of integers exactly once.

Can you help him to do that?

The first line contains a single integer n (2 ≤ n ≤ 1000). The second line contains the permutation P of integers between 1 and n.

Print “no” if it’s impossible to sort the permutation. Otherwise, print n(n−1)/2 lines that describe the pairs of values (not indices) to swap on the corresponding turn.