H, W = map(int, input().split())
mat = [input() for i in range(W)]
mat_t = [''.join(x) for x in zip(*mat)]
def check(mat, t):
    stack = set()
    for i, string in enumerate(mat):
        string = '.' + string + '.'
        for j in range(len(string)):
            if j+3<=len(string):
                if string[j:j+3] == '.#.':
                    if t==False:
                        stack.add((i, j))
                    else:
                        stack.add((j, i))
    return stack

stack1 = check(mat, False)
stack2 = check(mat_t, True)
if stack1 & stack2:
    print('No')
else:
    print('Yes')