def LCS_DYN(y, x):
    L = matrix
    LCS = []
    x_i, y_i = len(x), len(y)
    while x_i >= 0 and y_i >= 0:
        if x[x_i - 1] == y[y_i - 1]:
            LCS.append(x[x_i - 1])
            x_i, y_i = x_i - 1, y_i - 1
        elif L[x_i - 1][y_i - 1] == L[x_i][y_i]:
            x_i -= 1
            y_i -= 1
        elif L[x_i - 1][y_i] > L[x_i][y_i - 1]:
            x_i -= 1
        else:
            y_i -= 1
    LCS.reverse()
    return LCS