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