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 Go (1.14.1) (judge verdict: Wrong Answer)

package main

import (
	"fmt"
	"math"
)

type Item struct {
	Value  float64
	Weight float64
}

func main() {
	var ItemNumber int
	var MaxWeight float64
	sack := []Item{}

	fmt.Scanln(&ItemNumber, &MaxWeight)

	for i := 0; i < ItemNumber; i++ {
		X := Item{}
		fmt.Scanln(&X.Weight, &X.Value)
		sack = append(sack, X)
	}
	value, _ := Knapsack(sack,MaxWeight)
	fmt.Print(int64(value))
}


func combinations(items []Item, ch chan []Item) {
	defer close(ch)

	p := int(math.Pow(2., float64(len(items))))

	for i := 0; i < p; i++ {
		set := []Item{}
		for j := 0; j < len(items); j++ {
			if (i>>uint(j))&1 == 1 {
				set = append(set, items[j])
			}
		}
		ch <- set
	}
}

func getSackWeight(set []Item) (r float64) {
	for _, i := range set {
		r += i.Weight
	}
	return
}

func getSackValue(set []Item) (r float64) {
	for _, i := range set {
		r += i.Value
	}
	return
}

func Knapsack(items []Item, maxWeight float64) (float64, []Item) {
	bestVal := 0.
	bestSack := []Item{}

	ch := make(chan []Item)
	go combinations(items, ch)

	for sack := range ch {
		if getSackWeight(sack) <= maxWeight {
			v := getSackValue(sack)
			if v > bestVal {
				bestVal = v
				bestSack = sack
			}
		}
	}
	return bestVal, bestSack
}