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):
        if s[y][x]==".":
            continue

        for d in range(-1, 2, 2):
            xx = x + d
            yy = y + d
            if 0<=xx and xx<W:
                if s[y][xx]=="#":
                    print("Yes")
                    break
            if 0<=yy and yy<H:
                if s[yy][x]=="#":
                    print("Yes")
                    break
        else:
            continue

        break
    else:
        continue
    
    break
else:
    print("No")
    