Problem:
Score : 200 points

Problem Statement

There is a rectangle in the xy-plane, with its lower left corner at (0, 0) and its upper right corner at (W, H). Each of its sides is parallel to the x-axis or y-axis. Initially, the whole region within the rectangle is painted white.

Snuke plotted N points into the rectangle. The coordinate of the i-th (1 ≦ i ≦ N) point was (x_i, y_i).

Then, he created an integer sequence a of length N, and for each 1 ≦ i ≦ N, he painted some region within the rectangle black, as follows:

If a_i = 1, he painted the region satisfying x < x_i within the rectangle.

If a_i = 2, he painted the region satisfying x > x_i within the rectangle.

If a_i = 3, he painted the region satisfying y < y_i within the rectangle.

If a_i = 4, he painted the region satisfying y > y_i within the rectangle.

Find the area of the white region within the rectangle after he finished painting.

Constraints

1 ≦ W, H ≦ 100

1 ≦ N ≦ 100

0 ≦ x_i ≦ W (1 ≦ i ≦ N)

0 ≦ y_i ≦ H (1 ≦ i ≦ N)

W, H (21:32, added), x_i and y_i are integers.

a_i (1 ≦ i ≦ N) is 1, 2, 3 or 4.

Input

The input is given from Standard Input in the following format:

W H N
x_1 y_1 a_1
x_2 y_2 a_2
:
x_N y_N a_N

Output

Print the area of the white region within the rectangle after Snuke finished painting.

Sample Input 1

5 4 2
2 1 1
3 3 4

Sample Output 1

9

The figure below shows the rectangle before Snuke starts painting.

First, as (x_1, y_1) = (2, 1) and a_1 = 1, he paints the region satisfying x < 2 within the rectangle:

Then, as (x_2, y_2) = (3, 3) and a_2 = 4, he paints the region satisfying y > 3 within the rectangle:

Now, the area of the white region within the rectangle is 9.

Sample Input 2

5 4 3
2 1 1
3 3 4
1 4 2

Sample Output 2

0

It is possible that the whole region within the rectangle is painted black.

Sample Input 3

10 10 5
1 6 1
4 1 3
6 9 4
9 4 2
3 1 3

Sample Output 3

64

Solution in PyPy3 (7.3.0) (judge verdict: Accepted)

# import sys
# input = sys.stdin.readline
import itertools


# 持っているビスケットを叩き、1枚増やす
# ビスケット A枚を 1円に交換する
# 1円をビスケット B枚に交換する
def main():
    w, h, n = input_list()
    zahyou = [[0]*w for _ in range(h)]
    for _ in range(n):
        x, y, a = input_list()
        umeru(zahyou, x, y, a)
    ans = 0
    for hz in zahyou:
        ans += hz.count(0)
    print(ans)

def umeru(zu, x, y, a):
    for Y, row in enumerate(zu):
        for X, v in enumerate(row):
            if a == 1:
                if X < x:
                    zu[Y][X] = 1
            if a == 2:
                if X > x - 1:
                    zu[Y][X] = 1
            if a == 3:
                if Y < y:
                    zu[Y][X] = 1
            if a == 4:
                if Y > y - 1:
                    zu[Y][X] = 1


def input_list():
    return list(map(int, input().split()))


def input_list_str():
    return list(map(str, input().split()))


if __name__ == "__main__":
    main()