lst = []
l = []
str = input()
l = str.split(' ')
n = int(l[0])
no = int(l[1])
if no==0:
  print(n)
 

else:  
  str1 = input()
  lst = str1.split(' ')
  for i in range(0,no):
    lst[i] = int(lst[i])
  for i in range(1,100):
    if n-i not in lst :
      print(n-i)
      break
    if n+i not in lst:
      print(n+i)
      break
  
