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

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		long K = sc.nextLong();
		Number number[] = new Number [N];
		Main main = new Main();
		for (int i=0;i<N;i++) {
			Number num = main.new Number();
			num.a=sc.nextInt();
			num.b= sc.nextInt();
			number[i] =num;
		}
		Arrays.sort(number);
		long count =0;
		for (int i=0;i<N;i++) {
			count+=number[i].b;
			if (count>=K) {
				System.out.println(number[i].a);
				return;
			}
		}
	}
	public class Number implements Comparable<Number> {

		int a ;
		int b;
		@Override
		public int compareTo(Number o) {
			return this.a-o.a;
		}

	}
}