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.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        int[][] nums = new int[n][2];
        for (int i = 0; i < n; i++) {
            nums[i][0] = sc.nextInt();
            nums[i][1] = sc.nextInt();
        }
        
        Arrays.sort(nums, (a, b) -> Integer.compare(a[1], b[1]));
        Arrays.sort(nums, (a, b) -> Integer.compare(a[0], b[0]));
        
        int count = 0;
        for (int i = 0; i < n; i++) {
            count += nums[i][1];
            
            if (count >= k) {
                System.out.println(nums[i][0]);
                return;
            }
            
        }
    }
}