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)

X, N = map(int, input().split())
p_list = list(map(int, input().split()))

if N == 0:
  print(X)
else:
  p_list = sorted(p_list)
  all_range = list(range(102))
  A = [i for i in all_range if i not in p_list]
  B = [abs(i - X) for i in A]

  low = X - min(B)
  high = X + min(B)

  output = 0
  if high > 101:
    output = low
  if low < 0:
    output = high

  if output != 0:
    print(output)
  elif high in p_list:
    print(low)
  elif low in p_list:
    print(high)
  else:
    print(low)