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.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main {

    private static Scanner scan = new Scanner(System.in);

    public static void main(String[] args) {
	int N = scan.nextInt();
	int K = scan.nextInt();

	List<MyClass> list = new ArrayList<MyClass>(N);

	for (int i = 0; i < N; i++) {
	    int a = scan.nextInt();
	    int b = scan.nextInt();

	    list.add(new MyClass(a, b));
	}
	Collections.sort(list);

	int num = 0;
	for(MyClass l: list) {
	    num += l.b;
	    if(num >= K) {
		System.out.println(l.a);
		break;
	    }
	}
	scan.close();
    }
}

class MyClass implements Comparable<MyClass> {

    int a;
    int b;

    MyClass(int a, int b) {
	this.a = a;
	this.b = b;
    }

    @Override
    public int compareTo(MyClass o) {
	return a - o.a;
    }
}