Problem:
Score : 100 points

Problem Statement

There are N items, numbered 1, 2, \ldots, N.
For each i (1 \leq i \leq N), Item i has a weight of w_i and a value of v_i.

Taro has decided to choose some of the N items and carry them home in a knapsack.
The capacity of the knapsack is W, which means that the sum of the weights of items taken must be at most W.

Find the maximum possible sum of the values of items that Taro takes home.

Constraints

All values in input are integers.

1 \leq N \leq 100

1 \leq W \leq 10^5

1 \leq w_i \leq W

1 \leq v_i \leq 10^9

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 sum of the values of items that Taro takes home.

Sample Input 1

3 8
3 30
4 50
5 60

Sample Output 1

90

Items 1 and 3 should be taken.
Then, the sum of the weights is 3 + 5 = 8, and the sum of the values is 30 + 60 = 90.

Sample Input 2

5 5
1 1000000000
1 1000000000
1 1000000000
1 1000000000
1 1000000000

Sample Output 2

5000000000

The answer may not fit into a 32-bit integer type.

Sample Input 3

6 15
6 5
5 6
6 4
6 6
3 5
7 2

Sample Output 3

17

Items 2, 4 and 5 should be taken.
Then, the sum of the weights is 5 + 6 + 3 = 14, and the sum of the values is 6 + 6 + 5 = 17.

Solution in Haskell (GHC 7.10.3) (judge verdict: Accepted)

import Data.Array
import Data.Array.ST
import Data.Array.MArray
import Control.Monad
import Control.Monad.ST

solve n goods w = runST $ do
  dp <- newArray ((0,0), (n,w)) (-1)
  f dp 0 w where
    gary = listArray (0, n-1) goods
    f :: STUArray s (Int,Int) Int -> Int -> Int -> ST s Int
    f dp i j = do
      mem <- readArray dp (i, j)
      if mem /= -1 then
        return mem
      else do
        res <- res
        writeArray dp (i, j) res
        return res
      where
        (wi, vi) = gary ! i
        res
          | i == n = return 0
          | j < wi = nxt
          | otherwise = liftM2 max nxt nx'
          where
            nxt = f dp (i+1) j
            nx' = (+vi) <$> f dp (i+1) (j-wi)

main = do
  [n,w] <- map read.words <$> getLine
  goods <- replicateM n $ (\[a,b]->(a,b)).map read.words <$> getLine
  print $ solve n goods w