// Arup Guha
// Solution to 2012 Diviosn 2 South East Regional Problem E: Paint Me
// 11/10/2012

import java.util.*;

public class e {

	public static void main(String[] args) {

		Scanner stdin = new Scanner(System.in);

		int n, W, L, H, A, numW;

		// Get the room information.
		n = stdin.nextInt();
		W = stdin.nextInt();
		L = stdin.nextInt();
		H = stdin.nextInt();
		A = stdin.nextInt();
		numW = stdin.nextInt();

		// Add in the window info.
		int sub = 0;
		for (int i=0; i<numW; i++) {
			int tempL = stdin.nextInt();
			int tempW = stdin.nextInt();
			sub += (tempL*tempW);
		}

		while (n != 0) {

			// Get the area for n rooms.
			int area = 2*(L+W)*H+L*W - sub;
			area *= n;

			// Use int operations to get correct # cans of paint.
			int ans = 0;
			if (area%A == 0)
				ans = area/A;
			else
				ans = area/A + 1;

			System.out.println(ans);

			// Read in the next case.
			n = stdin.nextInt();
			W = stdin.nextInt();
			L = stdin.nextInt();
			H = stdin.nextInt();
			A = stdin.nextInt();
			numW = stdin.nextInt();

			// Start next case.
			sub = 0;
			for (int i=0; i<numW; i++) {
				int tempL = stdin.nextInt();
				int tempW = stdin.nextInt();
				sub += (tempL*tempW);
			}
		}
	}
}