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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;

public class Main {
	public static void main(String[] args) {

		Scanner scanner=new Scanner(System.in);

		int w=scanner.nextInt();
		int h=scanner.nextInt();
		int n=scanner.nextInt();

		Map<Integer,Integer> data=new TreeMap<Integer,Integer>();


			data.put(1,0);
			data.put(2,w);
			data.put(3,0);
			data.put(4,h);


		for(int i=0;i<n;i++) {
			int bufx=scanner.nextInt();
			int bufy=scanner.nextInt();
			int bufa=scanner.nextInt();

			if(bufa==1) {

				if(data.get(1)==0) {
					data.put(1,bufx);
				}else {
					if(bufx>data.get(1)) {
						data.put(1,bufx);
					}
				}
			}else if(bufa==2) {

				if(data.get(2)==w) {
					data.put(2,bufx);
				}else {
					if(bufx<data.get(2)) {
						data.put(2,bufx);
					}
				}


			}else if(bufa==3) {

				if(data.get(3)==0) {
					data.put(3,bufy);
				}else {

				if(bufy>data.get(3)) {
					data.put(3,bufy);
				}

				}
			}else {

				if(data.get(4)==h) {
					data.put(4,bufy);
				}else {
					if(bufy<data.get(4)) {
						data.put(4,bufy);
					}
				}
			}

		}

		int retwidth=data.get(2)-data.get(1);
		int retheight=data.get(4)-data.get(3);

		int result=retwidth*retheight;

		if(retwidth>0 && retheight>0) {
			System.out.println(result);
		}else {
			System.out.println("0");
		}

		scanner.close();

	}

	public static int getsumofkakuketa(int n) {

		int result=0;

		while(true) {

			result+=n%10;

			if(n/10!=0) {
				n/=10;
			}else {
				return result;
			}
		}



	}

	public static boolean isMacthed(int a,int b,int sum) {

		if(sum>=a && sum<=b) {
			return true;
		}else {
			return false;
		}

	}



}