from collections import Counter

H, W = map(int,input().split())
M = [input() for i in range(H)]

drct = [(0,1), (1,1), (1,0)]
cnt = 0
common = []

for y in range(H):
    for x in range(W):
        if M[y][x] == '.':
            continue
        cnt += 1
        for i,d in enumerate(drct):
            dy = y
            dx = x
            for j in range(W):
                dy += d[0]
                dx += d[1]
                if dy<=H-1 and dx<=W-1:
                    if M[dy][dx] == '#':
                        f = str(i) + str(j)
                        common.append(f)
                else:
                    break
                
if cnt == 0:
    print('NO')
    exit()

C = Counter(common).most_common()

for i in C:
    if i[1] == cnt//2:
        print('YES')
        break
else:
    print('NO')