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 Scala (2.11.7) (judge verdict: Accepted)

import scala.util.control.Breaks._

object Main extends App {
  val Array(n, k) = scala.io.StdIn.readLine.split(" ").map(_.toLong)

  val list = List.fill(n.toInt) { scala.io.StdIn.readLine.split(" ").map(_.toLong) }

  val sorted_list = list.sortBy(_.head)

  var count = 0L
  breakable {
    for (i <- sorted_list) {

      if (count + i(1) >= k) {
        println(i.head)
        break
      } else {
        count += i(1)
      }
    }
  }
}