Problem Statement

A shop sells N kinds of lunchboxes, one for each kind.
For each $i = 1, 2, \ldots, N$, the i-th kind of lunchbox contains A_i takoyaki (octopus balls) and B_i taiyaki (fish-shaped cakes).
Takahashi wants to eat X or more takoyaki and Y or more taiyaki.
Determine whether it is possible to buy some number of lunchboxes to get at least X takoyaki and at least Y taiyaki. If it is possible, find the minimum number of lunchboxes that Takahashi must buy to get them.
Note that just one lunchbox is in stock for each kind; you cannot buy two or more lunchboxes of the same kind.

Input

Input is given from Standard Input in the following format:
N
X Y
A_1 B_1
A_2 B_2
$\vdots$
A_N B_N

Output

If Takahashi cannot get at least X takoyaki and at least Y taiyaki, print -1; otherwise, print the minimum number of lunchboxes that he must buy to get them.

Constraints

• $1 \leq N \leq 300$
• $1 \leq X, Y \leq 300$
• $1 \leq A_i, B_i \leq 300$
• All values in input are integers.

Sample Input 1

3
5 6
2 1
3 4
2 3

Sample Output 1

2

He wants to eat 5 or more takoyaki and 6 or more taiyaki.
Buying the second and third lunchboxes will get him 3 + 2 = 5 taiyaki and 4 + 3 = 7 taiyaki.

Sample Input 2

3
8 8
3 4
2 3
2 1

Sample Output 2

-1

Even if he is to buy every lunchbox, it is impossible to get at least 8 takoyaki and at least 8 taiyaki.
Thus, print -1.

见题面 Input 部分

见题面 Output 部分