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=(int(i) for i in input().split())
if(n==0):
  print(x)
else:
  l=sorted([int(i) for i in input().split()])
  if(x not in l):
    print(x)
  else:
    k=l.index(x)
    c1,c2=0,0
    for i in range(k-1,-1,-1):
      if(x-l[i]>k-i):
        c1=l[i+1]-1
        break
    if(c1==0):
      c1=l[0]-1
    for i in range(k+1,n):
      if(l[i]-x>i-k):
        c2=l[i-1]+1
        break
    if(c2==0):
      c2=l[n-1]+1
    if(x-c1>c2-x):
      print(c2)
    else:
      print(c1)