Problem:
Score : 400 points

Problem Statement

You have N items and a bag of strength W.
The i-th item has a weight of w_i and a value of v_i.

You will select some of the items and put them in the bag.
Here, the total weight of the selected items needs to be at most W.

Your objective is to maximize the total value of the selected items.

Constraints

1 ≤ N ≤ 100

1 ≤ W ≤ 10^9

1 ≤ w_i ≤ 10^9

For each i = 2,3,...,N, w_1 ≤ w_i ≤ w_1 + 3.

1 ≤ v_i ≤ 10^7

W, each w_i and v_i are integers.

Input

Input is given from Standard Input in the following format:

N W
w_1 v_1
w_2 v_2
:
w_N v_N

Output

Print the maximum possible total value of the selected items.

Sample Input 1

4 6
2 1
3 4
4 10
3 4

Sample Output 1

11

The first and third items should be selected.

Sample Input 2

4 6
2 1
3 7
4 10
3 6

Sample Output 2

13

The second and fourth items should be selected.

Sample Input 3

4 10
1 100
1 100
1 100
1 100

Sample Output 3

400

You can take everything.

Sample Input 4

4 1
10 100
10 100
10 100
10 100

Sample Output 4

0

You can take nothing.

Solution in Haskell (GHC 7.10.3) (judge verdict: Time Limit Exceeded)

import Control.Monad
import Data.List

main = do
  li <- getLine
  let [n,w] = map read $ words li
  wvs <- forM [1..n] (\_ -> do
    li <- getLine
    let [w,v] = map read $ words li
    return (w,v)
    )
  let ans = compute w wvs
  print ans

{-
単純に総当たりで、前から順に入れたり入れなかったりしてみる
ただし袋が破れるなら入れない
とするなら、重いものを先に入れてみる方が枝刈りが起きやすいか？
-}

compute :: Int -> [(Int,Int)] -> Int
compute w wvs = maximum $ map snd $ loop [(0,0)] wvs
  where
--    wvs1 = reverse $ sort wvs
    loop awvs [] = awvs
    loop awvs ((wi,vi):wvs) = loop awvs' wvs
      where
        awvs' = [ (aw1, av+vi) | (aw,av) <- awvs, let aw1 = aw + wi, aw1 <= w ] ++ awvs