Problem:
Score : 300 points

Problem Statement

Given are an integer X and an integer sequence of length N: p_1, \ldots, p_N.

Among the integers not contained in the sequence p_1, \ldots, p_N (not necessarily positive), find the integer nearest to X, that is, find the integer whose absolute difference with X is the minimum. If there are multiple such integers, report the smallest such integer.

Constraints

1 \leq X \leq 100

0 \leq N \leq 100

1 \leq p_i \leq 100

p_1, \ldots, p_N are all distinct.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

X N
p_1 ... p_N

Output

Print the answer.

Sample Input 1

6 5
4 7 10 6 5

Sample Output 1

8

Among the integers not contained in the sequence 4, 7, 10, 6, 5, the one nearest to 6 is 8.

Sample Input 2

10 5
4 7 10 6 5

Sample Output 2

9

Among the integers not contained in the sequence 4, 7, 10, 6, 5, the ones nearest to 10 are 9 and 11. We should print the smaller one, 9.

Sample Input 3

100 0

Sample Output 3

100

When N = 0, the second line in the input will be empty. Also, as seen here, X itself can be the answer.

Solution in JavaScript (Node.js 12.16.1) (judge verdict: Wrong Answer)

function main(input) {
  input = input.trim()
  const args = input.split("\n")

  args[0] = args[0].split(" ")
  const x = Number(args[0][0])
  const n = Number(args[0][1])

  if (n === 0) return console.log(x)

  const pArray = args[1]
                  .split(" ")
                  .map(v => Number(v))
                  .sort((a, b) => a - b)

  const min = Math.min(x, pArray[0])
  const max = Math.max(x, pArray[n - 1])
  let last = null
  for (let i = min; i <= max + 1; i++) {
    if (pArray.includes(i) || i === x) continue

    const diff = Math.abs(x - i)
    if (!last) {
      last = { value: i, diff }
      continue
    }

    if (diff < last.diff) {
      last = { value: i, diff }
      continue
    }
    console.log(last.value)
    break
  }
}

main(require("fs").readFileSync("/dev/stdin", "utf8"))