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: Wrong Answer)

import math

X, N = list(map(int, input().split()))
p = list(map(int, input().split()))
# print(X, N, p)

if N == 0:
    print(X)
    exit()

p.sort()

minimum = p[0]
maximum = p[len(p) - 1]
# print(minimum, maximum)

if X < minimum or maximum < X:
    print(X)
    exit()

diff_min = abs(X - minimum - 1)
diff_max = abs(X - maximum + 1)
answer = minimum - 1 if diff_min < diff_max else maximum + 1
for candidate in range(minimum, maximum):
    if candidate in p: continue

    diff_answer = abs(X - answer)
    diff_candidate = abs(X - candidate)
    # print(candidate, diff, answer)
    if diff_candidate == diff_answer:
        answer = min(answer, candidate)
    elif diff_candidate < diff_answer:
        answer = candidate

print(answer)