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: Accepted)

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws IOException {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		long k = scanner.nextLong();
		List<P> list = new ArrayList<>();

		for(int i = 0; i < n; i++){
			list.add(new P(scanner.nextInt(), scanner.nextInt()));
		}

		list.sort((a,b) -> a.n - b.n);
		long count = 0;
		for(int i = 0; i < n; i++){
			count += list.get(i).k;
			if(count > k - 1){
				System.out.println(list.get(i).n);
				break;
			}
		}
	}
}

class P{
	int n;
	int k;
	public P(int n, int k) {
		this.n = n;
		this.k = k;
	}
}