#include <fstream>
#include <iomanip>

using namespace std;

ifstream fin("maria.in");
ofstream fout("maria.out");

int n, m, p, q;
int k;
int a[1001][1001];
int sum[1001][1001];

int cautaLocuri(int p, int q)
{
    int locuri = 0;
    int s;
    int x1, y1, x2, y2;
    for (int i = 1; i <= n - p + 1; ++i)
    {
        for (int j = 1; j <= m - q + 1; ++j)
        {
            x1 = i;
            y1 = j;
            x2 = i + p - 1;
            y2 = j + q - 1;
            s = sum[x2][y2] - sum[x2][y1 - 1] - sum[x1 - 1][y2] + sum[x1 - 1][y1 - 1];
            if (s == 0)
                ++locuri;
        }
    }
    return locuri;
}

int main()
{
    fin >> n >> m >> p >> q;
    fin >> k;
    int x, y;
    for (int i = 1; i <= k; ++i)
    {
        fin >> x >> y;
        a[x][y] = 1;
    }
    for (int i = 1; i <= n; ++i)
    {
        for (int j = 1; j <= m; ++j)
        {
            sum[i][j] = a[i][j] + sum[i - 1][j] + sum[i][j - 1] - sum[i - 1][j - 1];
        }
    }
    int cnt = 0;
    cnt += cautaLocuri(p, q);
    cnt += cautaLocuri(q, p);
    fout << cnt;

    return 0;
}