H, W = map(int,input().split())

s = []
for i in range(H):
    ss = input()
    s.append(ss)

shift = [[1,0],[-1,0],[0,1],[0,-1]]

for j in range(H):
    for i in range(W):
        if s[j][i] == "#":
            flag = False
            for dx, dy in shift:
                nx = i + dx
                ny = j + dy
                if nx >= 0 and nx < W and ny >= 0 and ny < H:
                    if s[ny][nx] == "#":
                        flag = True
            if not flag:
                exit(0)

if flag:
    print("Yes")
else:
    print("No")
