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: Runtime Error)

import sys
import bisect

def I(): return int(sys.stdin.readline().rstrip())
def LI():return list(map(int,sys.stdin.readline().rstrip().split()))
def LS():return list(sys.stdin.readline().rstrip().split())


def main():
  X,N = LI()[:]
  if N > 0:
    P = LI()
    P.sort()
  else:
    print(X)
    exit()
    
  index = bisect.bisect_left(P, X)
  if index >= N :
    print(X)
    exit()
    
  l = index
  r = index
  for i in range(0,200):
    up = X + i
    down = X - i
    
    if l < 0:
      print(down)
      break
    
    if r > N:
      print(up)
      break
     
    # Left優先
    if P[l] != down:
      print(down)
      break
     
    if P[r] != up:
      print(up)
      break
    
    l -= 1
    r += 1
    
if __name__ == '__main__':
	main()