H, W = map(int, input().split())
S = [list(input()) for _ in range(H)]

count = 0
pa = 0
for i in range(H):
    for j in range(W):
        a = S[i][j]
        if a == '#':
            if j-1 >= 0 and S[i][j-1] == '#':
                count += 1
            if j+1 <= W-1 and S[i][j+1] == '#':
                count += 1
            if i-1 >= 0 and S[i-1][j] == '#':
                count += 1
            if i+1 <= H-1 and S[i+1][j] == '#':
                count += 1

            if count >= 1:
                continue
            else:
                pa += 1
                break
if pa != 0:
    print('No')
else:
    print('Yes')
