Problem:
Score : 300 points

Problem Statement

There is an empty array.
The following N operations will be performed to insert integers into the array.
In the i-th operation (1≤i≤N), b_i copies of an integer a_i are inserted into the array.
Find the K-th smallest integer in the array after the N operations.
For example, the 4-th smallest integer in the array \{1,2,2,3,3,3\} is 3.

Constraints

1≤N≤10^5

1≤a_i,b_i≤10^5

1≤K≤b_1…+…b_n

All input values are integers.

Input

Input is given from Standard Input in the following format:

N K
a_1 b_1
:
a_N b_N

Output

Print the K-th smallest integer in the array after the N operations.

Sample Input 1

3 4
1 1
2 2
3 3

Sample Output 1

3

The resulting array is the same as the one in the problem statement.

Sample Input 2

10 500000
1 100000
1 100000
1 100000
1 100000
1 100000
100000 100000
100000 100000
100000 100000
100000 100000
100000 100000

Sample Output 2

1

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.TreeMap;
import java.util.StringTokenizer;
import java.util.Map;
import java.util.Map.Entry;
import java.io.BufferedReader;
import java.util.Comparator;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author SimplyDivine
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        FastReader in = new FastReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC {
        public void solve(int testNumber, FastReader in, PrintWriter out) {
            int n = in.nextInt();
            int k = in.nextInt();
            int a[] = new int[n];
            int b[] = new int[n];
            int freq[] = new int[(int) 1e5 + 1];

            Map<Integer, Integer> mp = new TreeMap<Integer, Integer>(
                    new Comparator<Integer>() {

                        public int compare(Integer o1, Integer o2) {
                            return o1.compareTo(o2);
                        }
                    }
            );
            for (int i = 0; i < n; i++) {
                a[i] = in.nextInt();
                b[i] = in.nextInt();
                mp.put(a[i], mp.getOrDefault(a[i], 0) + b[i]);
            }
            int sum = 0;
            for (Map.Entry<Integer, Integer> entry : mp.entrySet()) {
                k -= entry.getValue();
                if (k <= 0) {
                    out.println(entry.getKey());
                    break;
                }
            }

        }

    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader(InputStream i) {
            br = new BufferedReader(new
                    InputStreamReader(i));
        }

        public String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}