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.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

public class Main {

	public static class Pair {
		int a, b;
		Pair(int a, int b) {
			this.a = a;
			this.b = b;
		}
	}

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int k = sc.nextInt();
		Pair[] p = new Pair[n];
		for(int i = 0 ; i < n ; i++) {
			int a = sc.nextInt();
			int b = sc.nextInt();
			p[i] = new Pair(a, b);
		}
		Arrays.sort(p, new Comparator<Pair>() {
			public int compare(Pair p1, Pair p2) {
				return p1.a - p2.a;
			}
		});
		for(int i = 0 ; i < p.length ; i++) {
			k -= p[i].b;
			if(k <= 0) {
				System.out.println(p[i].a);
				return;
			}
		}
	}
}