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)

# -*- coding: utf-8 -*-

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

P_set = list(set(P))
#print(P_set)
#print(P_set[1])

ans_chk = 0

if ( X < P[0] or X > P[N-1] ):
  print(X)
  ans_chk = 1

if ( ans_chk==0 ):
  for i in range(len(P)):
    if ( P_set[i] == X ):
      X_i = i
      break
    elif ( P_set[i] > X ):
      print(X)
      ans_chk = 1
      break

if ( ans_chk==0 ):
  
  if ( X_i >= N-(X_i+1) ):
    M = N-(X_i+1)
    temp_ans = X + N-(X_i+1) +1
  else:
    M = X_i
    temp_ans = X - X_i -1
  
  for i in range(1,M+1):
    if ( P_set[ X_i -i ] != X-i ):
      print(X-i)
      ans_chk = 1
      break
    elif ( P_set[ X_i +i ] != X+i ):
      print(X+i)
      ans_chk = 1
      break

if ( ans_chk==0 ):
  print(temp_ans)