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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.*;
import java.util.*;
import java.util.Map.Entry;

public class Main {
		
	public static void main(String[] args) throws IOException {
		FastScanner sc = new FastScanner(System.in);
		
		int N = sc.nextInt();
		int W = sc.nextInt();
		ArrayList<ArrayList<Integer>> list = new ArrayList<ArrayList<Integer>>();
		for(int i = 0; i <= 3; i++) list.add(new ArrayList<Integer>());
		
		long w1 = sc.nextLong();
		list.get(0).add(sc.nextInt());
		for(int i = 1; i < N; i++){
			int w = sc.nextInt() - (int)w1;
			int v = sc.nextInt();
			list.get(w).add(v);
		}
		
		for(int i = 0; i <= 3; i++){
			Collections.sort(list.get(i), Collections.reverseOrder());
		}
		
		long ans = 0;
		
		for(int i = 0; i <= list.get(0).size(); i++){
			long sumW0 = w1 * i;
			if(sumW0 > W) continue;
			for(int j = 0; j <= list.get(1).size(); j++){
				long sumW1 = sumW0 + (w1 + 1) * j;
				if(sumW1 > W) continue;
				for(int k = 0; k <= list.get(2).size(); k++){
					long sumW2 = sumW1 + (w1 + 2) * k;
					if(sumW2 > W) continue;
					for(int m = 0; m <= list.get(3).size(); m++){
						long sumW3 = sumW2 + (w1 + 3) * m;
						if(sumW3 > W) continue;
						
						long res = 0;
						for(int ii = 0; ii < i; ii++) res += list.get(0).get(ii);
						for(int ii = 0; ii < j; ii++) res += list.get(1).get(ii);
						for(int ii = 0; ii < k; ii++) res += list.get(2).get(ii);
						for(int ii = 0; ii < m; ii++) res += list.get(3).get(ii);
						
						ans = Math.max(ans, res);
					}
				}
			}
		}
		
		System.out.println(ans);
		
	}//end main
	
}//end Main

class FastScanner {
    private InputStream in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    public FastScanner(InputStream in) {
		this.in = in;
	}
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() {
    	if (hasNextByte()) return buffer[ptr++];
    	else return -1;
    }
    private static boolean isPrintableChar(int c){
    	return 33 <= c && c <= 126;
    }
    public boolean hasNext() {
    	while(hasNextByte() && !isPrintableChar(buffer[ptr]))
    		ptr++; return hasNextByte();
    }
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble() {
    	return Double.parseDouble(next());
    }
}