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 Kotlin (1.0.0) (judge verdict: Wrong Answer)

import java.util.*

fun main(args: Array<String>) {
    val sc = Scanner(System.`in`)
    val n = sc.nextInt()
    val k = sc.nextLong()
    val a = (0 until n).map { Class016c(sc.next().toLong(), sc.next().toLong()) }
    println(problem061c(n, k, a))
}

fun problem061c(n: Int, k: Long, a: List<Class016c>): Long {
    var k2 = k
    var ans = 0L
    for (i in 0 until n) {
        val tmp = a[i].b
        if (tmp < k2) {
            k2 -= tmp
        } else {
            ans = a[i].a
            break
        }
    }
    return ans
}

data class Class016c(var a: Long, var b: Long)