H, W = map(int, input().split())
s=[]

for i in range(0, H):
    s.append(input())

for y in range(0, H):
    for x in range(0, W):
        c=0
        for dx in range(-1, 2):
            xx = x + dx
            if 0<=xx and xx<W:
                if s[y][xx]=="#":
                    c+=1
        if c>=3:
            print("Yes")
            break

        c=0
        for dy in range(-1, 2):
            yy = y + dy
            if 0<=yy and yy<H:
                if s[yy][x]=="#":
                    c+=1
        if c>=3:
            print("Yes")
            break
    else:
        continue
    
    break
else:
    print("No")
    