#python 3
def surfaceArea(A):
    # Area of top, bottom, and front
    area = 2 * len(A[0]) * len(A) + sum(A[-1])
    for i, row in enumerate(A):
        #reset h for each row
        h = 0
        for j, stack in enumerate(row):
            #add left edge
            area += abs(stack - h)
            #add back edge
            area += abs(stack - (0 if i == 0 else A[i-1][j]))
            #update h to current stack
            h = stack
        #add right edge of final stack
        area += h
    return area