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 PyPy3 (7.3.0) (judge verdict: Wrong Answer)

def resolve():
    import sys
    input = sys.stdin.readline
    # 整数 1 つ
    # n = int(input())
    # 整数複数個
    x, n = map(int, input().split())
    # 整数 N 個 (改行区切り)
    # N = [int(input()) for i in range(N)]
    # 整数 N 個 (スペース区切り)
    # N = list(map(int, input().split()))
    # 整数 (縦 H 横 W の行列)
    # A = [list(map(int, input().split())) for i in range(H)]

    if n == 0:
        print(x)
    else:
        P = list(map(int, input().split()))
        P.sort()
        #B = [i for i in range(102)]

        if x not in P:
            print(x)
        else:
            xindex = P.index(x)

            for j in range(1,100):
                if xindex - j >= 0:
                    if P[xindex - j] != x-j:
                        print(x-j)
                        break
                else:
                    print(x-j)
                if xindex + j <= n-1:
                    if P[xindex + j] != x+j:
                        print(x+j)
                        break
                else:
                    print(x+j)

resolve()