import java.io.*; // Java I/O
import java.util.*;

public class Problem4
{

    public static void main (String args[]) throws IOException
    {

	BufferedReader input =
	    new BufferedReader (new FileReader ("DATA41.txt"));
	PrintWriter output =
	    new PrintWriter (new FileWriter ("OUT41.txt"));

	for (int cases = 0 ; cases < 5 ; cases++)
	{
	    int types = Integer.parseInt (input.readLine ());
	    int[] [] blocks = new int [2] [types];
	    for (int i = 0 ; i < types ; i++)
	    {
		StringTokenizer st = new StringTokenizer (input.readLine ());
		blocks [0] [i] = Integer.parseInt (st.nextToken ());
		blocks [1] [i] = Integer.parseInt (st.nextToken ());
	    }
	    int total = Integer.parseInt (input.readLine ());
	    for (int y = 0 ; y < blocks [0].length - 1 ; y++)
	    {
		for (int z = y + 1 ; z < blocks [0].length ; z++)
		{
		    if (blocks [0] [y] < blocks [0] [z])
		    {
			int temp = blocks [0] [y];
			int temp2 = blocks [1] [y];
			blocks [0] [y] = blocks [0] [z];
			blocks [1] [y] = blocks [1] [z];
			blocks [0] [z] = temp;
			blocks [1] [z] = temp2;
		    }
		}
	    }
	    int[] heights = new int [total + 1];
	    for (int i = 1 ; i < heights.length ; i++)
	    {
		heights [i] = -1;
	    }
	    int[] [] b = new int [heights.length] [types];
	    for (int i = 1 ; i <= total ; i++)
	    {
		int min = Integer.MAX_VALUE;
		int minClub = -1;
		for (int j = 0 ; j < types ; j++)
		{
		    try
		    {
			if (b [i - blocks [0] [j]] [j] + 1 <= blocks [1] [j])
			{
			    if (heights [i - blocks [0] [j]] + 1 < min && heights [i - blocks [0] [j]] != -1)
			    {
				min = heights [i - blocks [0] [j]] + 1;
				minClub = j;
			    }
			}
		    }
		    catch (ArrayIndexOutOfBoundsException e)
		    {
		    }
		}
		if (min != Integer.MAX_VALUE)
		{
		    heights [i] = min;
		    for (int k = 0 ; k < types ; k++)
		    {
			b [i] [k] = b [i - blocks [0] [minClub]] [k];
		    }
		    b [i] [minClub]++;
		}
	    }
	}
	output.close ();
    }
}