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.nio.charset.IllegalCharsetNameException;
import java.util.*;
import java.lang.*;


public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int k = sc.nextInt();
		int[] a = new int[n];
		int[] b = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = sc.nextInt();
			b[i] = sc.nextInt();
		}
		Map<Integer, Integer> map = new TreeMap<>();
		for (int i = 0; i < n; i++) {
			if (map.containsKey(a[i])) {
				map.put(a[i], map.get(a[i]) + b[i]);
			} else {
				map.put(a[i], b[i]);
			}
		}
		for (int i = 1; i <= 100000; i++) {
			if (map.containsKey(i)) {
				k -= map.get(i);
			}
			if (k <= 0) {
				System.out.println(i);
				break;
			}
		}
	}
}