uu = list(map(int,input().split()))
h = uu[0]
w = uu[1]
arr = []
for i in range(0, h):
    arr.append(list(map(lambda x: x == "#", list(input()))))
res = True
for i in range(0, (h - 1)):
    for j in range (0, (w - 1)):
        if arr[i][j]:
            if (not arr[i + 1][j]) and (not arr[i][j + 1]):
                res = False
                break
    if not res:
        break
if res:
    print("Yes")
else:
    print("No")