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 Python (3.8.2) (judge verdict: Accepted)

def main():
  ## IMPORT MODULE
  #import sys

  #sys.setrecursionlimit(100000)
  #input=lambda :sys.stdin.readline().rstrip()

  #f_inf=float("inf")
  #MOD=10**9+7
  
  if 'get_ipython' in globals(): 
    ## SAMPLE INPUT
    x, n = 6, 5
    P = [4, 7, 10, 6, 5]

  else:
    ##INPUT 
    #n = input()
    x, n = map(int, input().split())
    if n == 0:
      P = []
    else: 
      P = list(map(int, input().split()))

  ## SUBMITION CODES HERE
  for i in range(1, 100):
    if x - i not in P:
        dif_mis = x-i
        break

  for i in range(0, 100):
    if x + i not in P:
        dif_pls = x+i
        break

  if (x-dif_mis)**2 > (x-dif_pls)**2:
    print(dif_pls)
  else:
    print(dif_mis)

main()