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 PHP7 (7.0.15) (judge verdict: Wrong Answer)

<?php

fscanf(STDIN,"%d%d",$n,$k);

$a = array();
$bs = array();

$Array = [];
$totalArray = [];

foreach ($bs as $b => $key){
    for ($ai = 0; $ai < $n; $ai++) {
        if ($a[$ai] === $a[$key]){
            for ($ti = 1; $ti <= $b[$key]; $ti++){
                $totalArray[] = $a[$ai];

            }
        }
    }
}

$totalArrayRsort = rsort($totalArray);

echo $totalArrayRsort[$k];