Contest Duration: - (local time) (100 minutes) Back to Home
D - Strange Lunchbox /

Time Limit: 2 sec / Memory Limit: 1024 MB

### 問題文

N 種類の弁当が、それぞれ 1 個ずつ売られています。
i = 1, 2, \ldots, N について、i 種類目の弁当には A_i 個のたこ焼きと B_i 個のたい焼きが入っています。

### 制約

• 1 \leq N \leq 300
• 1 \leq X, Y \leq 300
• 1 \leq A_i, B_i \leq 300
• 入力はすべて整数

### 入力

N
X Y
A_1 B_1
A_2 B_2
\vdots
A_N B_N


### 入力例 1

3
5 6
2 1
3 4
2 3


### 出力例 1

2


### 入力例 2

3
8 8
3 4
2 3
2 1


### 出力例 2

-1


よって、-1 を出力します。

Score : 400 points

### 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.

### 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.

### 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.

### 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.