zid

Ionel is in the 1st grade but he doesn't like Math and he prefers playing with cubes.
Starting from Ionel's passion, his father tries to propose all sorts of problems to Ionel, which he would solve without actually realizing he's doing Math.
One day Ionel built n towers made up of h₁, h₂, ..., and respectively h_n cubes (each cube having sides of length 1).
His father proposed to him: "Let's make a wall of length n! Pick some of the n towers you've built so that by rearranging the cubes from them you can make a wall of length n. The wall must be formed of n towers of the same height."

Task

Write a program that reads n, the number of towers, as well as the heights of all the towers built by Ionel and which determines which towers could be chosen so that we can make a wall of length n.

Input Data

Input file zid.in contains on the first line a positive integer n representing the number of towers.
The second line contains n positive integers each separated by a space, representing the heights of the n towers.

Output Data

Output file zid.out will contain on the first line a positive integer k, which represents the number of towers chosen to build the wall.
The second line will contain k positive integers separated by a space, representing the heights of the k towers selected for building the wall.

Constraints and Statements

• 0 < n <= 1000
• 0 < h_i <= 1000, for any i=1, 2, …, n
• The height of the constructed wall must be at least 1.
• If there is more than one solution you will display only one.
  

Time limit: 0.1 seconds/test

prof. Marinel Serban
Computer Science "Grigore Moisil" Iasi
Contact:marinel_serban@yahoo.com