N, K = map(int, input().split())
A = list(map(int, input().split()))
A.sort()
from bisect import *
def binary_search(A,p):
  if A[0]<=p and p<=A[-1]:
    if p == A[bisect_left(A,p)]:
      return True
  return False

while A:
  if len(A)>=3 and A[-1]-A[-2]==A[-2]-A[-3]==1:
    print('No')
    break
  a = A.pop()
  if a==1:
    print('No')
    break
  lis = []
  while A:
    b = A.pop()
    lis.append(b)
    if a-b>5:
      break
    if (a-b)%2==1:
      p = b-(3-(a-b)//2)
      if p>=1:
        insort(A,p)
  for l in lis:
    if len(A)==0:
      A.append(l)
    elif not binary_search(A,l):
      insort(A,l)
else:
  print('Yes')