## Problem Description

There are N items in the supermarket, each of them with a normal price Ai and sale price Bi.

Rar the Cat wants to buy X items during the non-sale period, and Y items during a sale period, without buying two of the same items.

Help Rar minimise the total cost of the items he buys.

## Input

The first line of input will contain three integers, N, X and Y.

The next N lines of input will contain two integers each, representing Ai and Bi.

## Output

The output should contain one integer, the minimum total cost.

## Limits

0 ≤ X, Y ≤ N, X + Y ≤ N, 0 ≤ Ai, Bi ≤ 109.

Subtask 1 (4%): 1 ≤ N ≤ 12.

Subtask 2 (10%): 1 ≤ N ≤ 50.

Subtask 3 (14%): 1 ≤ N ≤ 300.

Subtask 4 (14%): 1 ≤ N ≤ 2 000.

Subtask 5 (7%): 1 ≤ N ≤ 100 000, Bi = 0.

Subtask 6 (13%): 1 ≤ N ≤ 100 000, Y = 1.

Subtask 7 (12%): 1 ≤ N ≤ 100 000, X + Y = N.

Subtask 8 (11%): 1 ≤ N ≤ 100 000.

Subtask 9 (15%): 1 ≤ N ≤ 500 000.

```3 1 1
1 3
4 1
5 6```

`2`

## Sample Testcase 2

```4 2 1
3 4
0 3
4 5
3 10```

`7`

### Submitting .cpp to 'sale'

Time Limit: 1 Seconds
Memory Limit: 1024MB