h, w = map(int, input().split())
s_input = []
for i in range(h):
    s_input.append(input())

can_draw = True

for i in range(h):
    for j in range(w):
        if s_input[i][j] == '#':
            if i - 1 >= 0:
                if s_input[i-1][j] == '#':
                    #ok
                    continue
            if j - 1 >= 0:
                if s_input[i][j - 1] == '#':
                    #ok
                    continue
            if j + 1 <= w:
                if s_input[i][j + 1] == '#':
                    #ok
                    continue
            if i + 1 <= h:
                if s_input[i + 1][j] == '#':
                    #ok
                    continue
            can_draw = False
            break
    if not can_draw:
        break

print('Yes' if can_draw else 'No')