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)

def main():
    X, N = map(int, input().split())
    P = set(map(int, input().split()))
    M = [10**5]*201
    if len(P) == 0:
        print(X)
        return
    min_abs = 10**5
    for i in range(102):
        if X-i not in P and X+i not in P:
            if min_abs > abs(X-(X-i)):
                min_abs = min(min_abs, abs(X-(X-i)))
                M[min_abs] = min(M[min_abs], X-i)
            elif min_abs > abs(X-(X+i)):
                min_abs = min(min_abs, abs(X-(X+i)))
                M[min_abs] = min(M[min_abs], X+i)
        if X-i not in P:
            if abs(X-(X-i)) < min_abs:
                min_abs = abs(X-(X-i))
                M[min_abs] = min(M[min_abs], X-i)
        if X+i not in P:
            if abs(X-(X+i)) < min_abs:
                min_abs = abs(X-(X+i))
                M[min_abs] = min(M[min_abs], X+i)
    print(min(M))


if __name__ == "__main__":
    main()