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)

from bisect import bisect_left as bl
x,n = map(int, input().split())
p = list(map(int, input().split()))
if n == 0:
    print(x)
else:
    i = 0
    p.sort()
    a = bl(p, x)
    if a == n:
        print(x)
    elif p[a] != x:
        print(x)
    else:
        while(True):
            i += 1
            if p[bl(p, x-i)] != x-i:
                print(x-i)
                break
            else:
                a = bl(p, x+i)
                if a == n:
                    print(x+i)
                    break
                elif p[a] != x+i:
                    print(x+i)
                    break