# C
h, w = map(int, input().split())
s = [list(str(input())) for i in range(h)]

can = True
for i in range(h-1):
    for j in range(w-1):
        if s[i][j] == '#':
            cnt = 0
            if s[i][j+1] == '#':
                cnt += 1
            if j-1 > 0 and s[i][j-1] == '#':
                cnt += 1
            if s[i+1][j] == '#':
                cnt += 1
            if i-1 > 0 and s[i-1][j] == '#':
                cnt += 1
            if cnt > 0:
                continue
            else:
                can = False
                break
    if not can:
        break
if can:
    print('Yes')
else:
    print('No')