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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
#define ll long long int
#define ull unsigned long long int
#define pb push_back
#define faster ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define mem(ara,n) memset(ara,n,sizeof(ara))
#define memb(ara) memset(ara,false,sizeof(ara))
#define all(x) (x).begin(),(x).end()
#define fr freopen("input.txt","r",stdin);
#define fw freopen("output.txt","w",stdout);
const double PI  =3.141592653589793238463;
using namespace std;

int main()
{
    faster;
    ll a,b,c1,c2,r1,r2,d,e,f=0,ans=0,sum=0,m,h,n,p,q,r,t,w,x,y,z;
    string s;
    cin>>w>>h>>n;//w=x okhkho h=y okhkho
    r1=0;r2=w;c1=0;c2=h;
    char black[w+1][h+1];
    int ck=0;
while(n--)
{

    cin>>x>>y>>a;
    if(a==1)
    {
        r1=x;
        r2=w;
        c1=c1;
        c2=c2;
        for(int i=1;i<=r1;i++)
        {
            for(int j=1;j<=h;j++)
            {
                black[i][j]='b';
            }
        }
        //cout<<"a =1 "<<"r1="<<r1<<"r2="<<r2<<"c1="<<c1<<"c2="<<c2<<endl;

    }

   else if(a==2)
    {
        r1=r1;
        r2=x+1;
        c1=c1;
        c2=c2;
        for(int i=r2;i<=w;i++)
        {
            for(int j=1;j<=h;j++)
            {
                black[i][j]='b';
            }
        }
      //  cout<<"a =2 "<<"r1="<<r1<<"r2="<<r2<<"c1="<<c1<<"c2="<<c2<<endl;
    }
    else if(a==3)
    {
        r1=r1;
        r2=r2;
        c1=y;
        c2=c2;
        for(int i=1;i<=w;i++)
        {
            for(int j=1;j<=c1;j++)
            {
                black[i][j]='b';
            }
        }
      //  cout<<"a =3 "<<"r1="<<r1<<"r2="<<r2<<"c1="<<c1<<"c2="<<c2<<endl;
    }
     else
    {
        r1=r1;
        r2=r2;
        c1=c1;
        c2=y+1;
        for(int i=1;i<=w;i++)
        {
            for(int j=c2;j<=h;j++)
            {
                black[i][j]='b';
            }
        }
      // cout<<"a =4 "<<"r1="<<r1<<"r2="<<r2<<"c1="<<c1<<"c2="<<c2<<endl;
    }
}
for(int i=1;i<=w;i++)
        {
            for(int j=1;j<=h;j++)
            {
                if(black[i][j]=='b')
                {
                    continue;
                }
                else{
                    ck++;
                }
            }
        }

cout<<ck<<endl;


    return 0;
}