stack = [-1]
    h.append(0)
    maxA = 0
    for i in range(len(h)):
        while h[i] < h[stack[-1]]:
            height = h[stack.pop()]
            width = i - stack[-1] -1
            if height * width > maxA:
                maxA = height * width
        stack.append(i)
    return maxA