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)

x,n = map(int, input().split())

if n == 0:
    print(x)
    exit()

p = list(map(int,input().split()))

allList=[]

for i in range(-201,301):
    allList.append(i)

diff = set(allList) ^ set(p)



diff = list(diff)
diff.append(x)
diff = sorted(diff)

# print(diff)

ind = diff.index(x)
# print(ind)

# if x == 100:
    

a = diff[ind-1]
b = diff[ind+1]
# print(a,b)

ax = abs(x-a)
bx = abs(x-b)

# print(ax,bx)

if ax==bx:
    if a < b:
        print(a)
        exit()
    else:
        print(b)
        exit()

if ax > bx:
    print(b)
else:
    print(a)