H, W = map(int, input().split())
matrix1 = list(list(input()) for i in range(H))
for i in matrix1:
    for j in i:
        if matrix1[matrix1.index(i)][i.index(j)] == "#":
            if matrix1.index(i) - 1 >= 0 and matrix1[matrix1.index(i) - 1][i.index(j)] == '#':
                break
            elif i.index(j) - 1 >= 0 and matrix1[matrix1.index(i)][i.index(j) - 1] == '#':
                break
            elif i.index(j) + 1 <= len(i) - 1 and matrix1[matrix1.index(i)][i.index(j) + 1] == '#':
                break
            elif matrix1.index(i) + 1 <= len(matrix1) - 1 and matrix1[matrix1.index(i) + 1][i.index(j)] == '#':
                break
            else:
                print('No')
                exit()
print('Yes')
