CodeForces 635A Orchestra（水题）

题意：给你一个rxc的矩阵，其中有n个特殊的点，问有多少个子矩阵可以满足特殊的点大于等于k

思路：由于数据只有10....所以xib做就好

#include <cstdio>
#include <queue>
#include <cstring>
#include <iostream>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <map>
#include <string>
#include <set>
#include <ctime>
#include <cmath>
#include <cctype>
using namespace std;
#define maxn 100000
#define LL long long
int cas=1,T;
int a[12][12];
int r,c,n,k;
int check(int x,int x1,int y,int y1)
{
	int ans = 0;
	for (int i = x;i<=x1;i++)
		for (int j = y;j<=y1;j++)
			if (a[i][j])
				ans++;
	return ans;
}
int main()
{
	while (scanf("%d%d%d%d",&r,&c,&n,&k)!=EOF)
	{
		for (int i = 1;i<=n;i++)
		{
			int x,y;
			scanf("%d%d",&x,&y);
			a[x][y]=1;
		}
		int ans = 0;
		for (int i = 1;i<=r;i++)
			for (int j = i;j<=r;j++)
				for (int ii=1;ii<=c;ii++)
					for (int jj = ii;jj<=c;jj++)
						if (check(i,j,ii,jj)>=k)
							ans++;
		printf("%d\n",ans);
	}
	//freopen("in","r",stdin);
	//scanf("%d",&T);
	//printf("time=%.3lf",(double)clock()/CLOCKS_PER_SEC);
	return 0;
}

Description

Paul is at the orchestra. The string section is arranged in an r × c rectangular grid and is filled with violinists with the exception of nviolists. Paul really likes violas, so he would like to take a picture including at least k of them. Paul can take a picture of any axis-parallel rectangle in the orchestra. Count the number of possible pictures that Paul can take.

Two pictures are considered to be different if the coordinates of corresponding rectangles are different.

Input

The first line of input contains four space-separated integers r, c, n, k (1 ≤ r, c, n ≤ 10, 1 ≤ k ≤ n) — the number of rows and columns of the string section, the total number of violas, and the minimum number of violas Paul would like in his photograph, respectively.

The next n lines each contain two integers x_i and y_i (1 ≤ x_i ≤ r, 1 ≤ y_i ≤ c): the position of the i-th viola. It is guaranteed that no location appears more than once in the input.

Output

Print a single integer — the number of photographs Paul can take which include at least k violas.

Sample Input

Input

2 2 1 1
1 2

Output

4

Input

3 2 3 3
1 1
3 1
2 2

Output

1

Input

3 2 3 2
1 1
3 1
2 2

Output

4