uva 10703 - Free spots Solution in Python

while True:
    w, h, n = [int(x) for x in input().strip().split()]
    if w == 0 and h == 0 and n == 0:
        break
    ls = []
    for i in range(h):
        ls.insert(i, [0] * w)
    result = w * h
    for i in range(n):
        x1, y1, x2, y2 = [int(x) for x in input().strip().split()]
        if x1 > x2:
            x1, x2 = x2, x1
        if y1 > y2:
            y1, y2 = y2, y1
        x1 -= 1
        y1 -= 1

        for j in range(y1, y2):
            for k in range(x1, x2):
                if ls[j][k] == 0:
                    result -= 1
                    ls[j][k] = 1
    if result == 0:
        print("There is no empty spots.")
    elif result == 1:
        print("There is one empty spot.")
    else:
        print(f"There are {result} empty spots.")
    input()