python - Python3 Adding sum of list -

i stuck trying sum of lists. keep getting error int , can't sum. need convert lists else?

edit: added inputs beginning clarity.

sqft = int(input('input paint coverage in sq ft per gallon: ' )) wall = int(input('input number of walls: ')) window = int(input('input number of windows: ')) door = int(input('input number of doors: ')) wall1=[] # wall list lengths wall2=[] # wall list widths win1=[] # window list lengths win2=[] # window list widths d1=[] # door list lengths d2=[] # door list widths  x in range(1, (wall) +1):     print('input length of wall ', x, ':')     = [int(x) x in input().split(',')]     wall1.append(a)     print('input width of wall ', x, ':')     b = [int(x) x in input().split(',')]     wall2.append(b)    print(wall2, ':', wall1)   x in range(1, (window) +1):     print('input length of window ', x, ':')     c = [int(x) x in input().split()]     win1.append(c)     print('input width of window ', x, ':')     d = [int(x) x in input().split()]     win2.append(d) print(win2, ':', win1)   x in range(1, (door) +1):     print('input length of door', x, ':')     e = [int(x) x in input().split()]     d1.append(e)     print('input width of door ', x, ':')     f = [int(x) x in input().split()]     d2.append(f) print(d1, ':', d2)  def listsum(wall1):     if len(wall1) == 1:         return wall1[0]    else:         return wall1[0] + listsum(wall1[1:])  print(listsum(wall1))