H, W = map(int, input().split())
S = [['.']*W]
for i in range(H):
    S.append(['.'] + list(input()) + ['.'])
S.append(['.']*W)

for i in range(1, H+1):
    for j in range(1, W+1):
        if S[i][j] == '#':
            if S[i+1][j] == '.' and S[i-1][j] == '.' and S[i][j+1] == '.' and S[i][j-1] == '.':
                print('No')
                break
    else:
        continue
    break

else:
    print('Yes')