import java.io.*;
import java.util.*;
import java.util.stream.*;

public class Main {
    static long[][][] dp;
    static Juel[] juels;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int m = sc.nextInt();
        juels = new Juel[n];
        for (int i = 0; i < n; i++) {
            juels[i] = new Juel(sc.nextInt(), sc.nextInt());
        }
        Arrays.sort(juels);
        dp = new long[2][n][m + 1];
        for (long[][] arr1 : dp) {
            for (long[] arr2 : arr1) {
                Arrays.fill(arr2, -1);
            }
        }
        System.out.println(dfw(0, n - 1, m));
    }
    
    static long dfw(int type, int idx, int w) {
        if (w < 0) {
            return Integer.MIN_VALUE;
        }
        if (idx < 0) {
            return 0;
        }
        if (dp[type][idx][w] < 0) {
            dp[type][idx][w] = dfw(type, idx - 1, w);
            if (type == 0) {
                dp[type][idx][w] = Math.max(dp[type][idx][w], (dfw(1, idx - 1, w - juels[idx].weight) + juels[idx].value) * juels[idx].value);
            } else {
                dp[type][idx][w] = Math.max(dp[type][idx][w], (dfw(1, idx - 1, w - juels[idx].weight) + juels[idx].value));
            }
        }
        return dp[type][idx][w];
    }
    
    static class Juel implements Comparable<Juel> {
        int weight;
        int value;
        
        public Juel(int value, int weight) {
            this.weight = weight;
            this.value = value;
        }
        
        public int compareTo(Juel another) {
            return another.value - value;
        }
    }
}

class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}