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 Go (1.14.1) (judge verdict: Accepted)

package main

import (
  "fmt"
)

func main() {
  var x, n, tmp, min, max int
  fmt.Scanf("%d %d", &x, &n)
  target := make([]int, n)

  if n == 0 {
    fmt.Println(x)
  } else {

    for i := 0; i < n; i++ {
      fmt.Scanf("%d", &tmp)
      target[i] = tmp
    }

    for j := x; j >= 0; j--{
      isMin := true
      for _, v := range target {
        if j == v {
          isMin = false
          break
        }
      }

      if isMin {
        min = j
        break
      }
    }

    for k := x; k <= 101; k++ {

      isMax := true
      for _, v1 := range target {
        if k == v1 {
          isMax = false
          break
        }
      }

      if isMax {
        max = k
        break
      }
    }
    if x - min > max - x {
      fmt.Println(max)
    } else {
      fmt.Println(min)
    }
  }
}