B'Madeline has an array a of n integers. A pair (u, v) of integers forms an inversion in a if: Madeline recently found a magical paper, which allows her to write two indices u and v and swap the values a_u and a_v . Being bored, she decided to write a list of pairs (u_i, v_i) with the following conditions: Construct such a list or determine that no such list exists. If there are multiple possible answers, you may find any of them. The first line of the input contains a single integer n ( 1 <= n <= 1000 ) -- the length of the array. Next line contains n integers a_1,a_2,...,a_n (1 <= a_i <= 10^9) -- elements of the array. Print -1 if no such list exists. Otherwise in the first line you should print a single integer m ( 0 <= m <= dfrac{n(n-1)}{2} ) -- number of pairs in the list. The i -th of the following m lines should contain two integers u_i, v_i ( 1 <= u_i < v_i <= n ). If there are multiple possible answers, you may find any of them. In the first sample test case the array will change in this order [3,1,2] rightarrow [2,1,3] rightarrow [1,2,3] . In the second sample test case it will be [1,8,1,6] rightarrow [1,6,1,8] rightarrow [1,1,6,8] . In the third sample test case the array is already sorted. '...