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 PHP (5.6.30) (judge verdict: Time Limit Exceeded)

<?php
$input = explode(' ', trim(fgets(STDIN)));
$num = $input[0];
$order = $input[1] - 1;

$array = array();

for ($i=0; $i < $num; $i++) {
  $tmp = explode(' ', trim(fgets(STDIN)));
  $in = $tmp[0];
  $loop = $tmp[1];
  for ($j=0; $j < $loop; $j++) {
    $array[] = $in;
  }
}

sort($array);
echo $array[$order]."\n";