Given sequence a0, a1, ... an-1 of n unique integers, each belongs to the interval [0; n - 1]. The exchange is an operation (i, j) (0 ≤ i, j ≤ n - 1) that swaps the values ai and aj. Sort the sequence using the minimum number of exchanges. Print all exchanges.

Input

First line contains number n (n ≤ 106). Second line contains n different integers from the interval [0; n - 1].

Output

In the first line print the minimum number of exchanges k. In the next k lines print all performed exchanges as pairs (i, j).