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)

x, n = [int(i) for i in input().split(' ')]
if n > 0:
    p = [int(i) for i in input().split(' ')]

    p.append(x)
    p.sort()
    i = p.index(x)

    y = x
    double = 0

    for j in range(1, i + 1):
        if i == j:
            low = x - j - 1
        elif not x - j + double == p[i - j]:
            if x == p[i - j]:
                double += 1
            else:
                low = x - j + double
                break
    double = 0
    for j in range(1, len(p) - i + 1):
        if j + i == len(p):
            high = x + j + 1
        elif not x + j - double == p[i + j]:
            if x == p[i + j]:
                double += 1
            else:
                high = x + j - double
                break

    if x - low > high - x:
        print(high)
    else:
        print(low)
else:
    print(x)
    exit()