Hakuna Matata Sort

After a pleasant walk through the African valley, Timon and Pumbaa decided to have lunch. They took $n$ beetles out from under a rock and placed them on a nearby log. The beetles have distinct integer masses from $1$ to $n$. To make lunch more enjoyable, Pumbaa suggested eating the beetles in increasing order of mass.

To sort the beetles by increasing mass, Timon and Pumbaa use Hakuna Matata sort. In each move, they pick two beetles whose masses differ by at most one, and then swap them. For example, if Pumbaa picks the beetle with mass 2, Timon can take the beetle with mass 1 or mass 3. The two friends have used this sort many times, so they know it always works.

Zazu watched the whole process closely. He had never seen anything like it and wondered how beetles could be sorted this way. Your task is to write a program that takes the initial arrangement of the beetles and prints a sequence of moves that sorts them by increasing mass.

The first line contains the number of beetles $n$ ($1 \le n \le 100$). The second line contains $n$ distinct integers $m_i$ ($1 \le m_i \le n$) separated by spaces, where $m_i$ is the mass of the beetle with number $i$.

Print the number of moves $t$ on the first line. On each of the next $t$ lines, print two integers $i$ and $j$, meaning that on move $s$ Pumbaa took the beetle at position $i$ and Timon took the beetle at position $j$. Any sequence of moves that uses at most 50000 operations is accepted.