from operator import itemgetter
from itertools import *
from bisect import *
from collections import *
from heapq import *
import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def MI(): return map(int, sys.stdin.buffer.readline().split())
def MI1(): return map(int1, sys.stdin.buffer.readline().split())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SI(): return sys.stdin.buffer.readline()[:-1]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
dij = [(1, 0), (0, 1), (-1, 0), (0, -1)]

def solve(aa):
    fin=set(aa)
    aa = [-a for a in aa]
    heapify(aa)
    q = deque()

    def push(val):
        heappush(aa,-val)
        fin.add(val)

    while aa:
        a = -heappop(aa)
        while q and q[-1] > a+5: q.pop()
        if a-3 not in fin and a-3>0 and a+1 in q: push(a-3)
        if a-2 not in fin and a-2>0 and a+3 in q: push(a-2)
        if a-1 not in fin and a-1>0 and a+5 in q: push(a-1)
        if 1 in fin:return False
        q.appendleft(a)
        # print(aa,q,fin)
    return True

n,k=MI()
aa=LI()
if solve(aa):print("Yes")
else:print("No")