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.Scanner;

/**
 * https://abc061.contest.atcoder.jp/tasks/abc061_c
 */
public class Main {

	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		int N = Integer.parseInt(sc.next());
		int K = Integer.parseInt(sc.next());
		Item[] items = new Item[N];
		for(int i=0; i<N; i++){
			items[i] = new Item(Integer.parseInt(sc.next()),Integer.parseInt(sc.next()));
		}
		sc.close();
		
		Arrays.sort(items, (o1, o2) -> o1.a - o2.a );

		long current = 0;
		int index = 0;
		while(index<N && current+items[index].b<K){
			current = current+items[index].b;
			index++;
		}
		
		
		System.out.println(items[index].a);
		
	}
	
	static class Item{
		int a;
		int b;
		Item(int a, int b){
			this.a = a;
			this.b = b;
		}
	}

}