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 (7.4.4) (judge verdict: Accepted)

<?php
  fscanf(STDIN, "%d%d", $n, $k);
  $vals = [];
  $counts = [];
  for($i=0; $i<$n; $i++){
      fscanf(STDIN, "%d%d", $a, $b);
      $vals[$i] = $a;
      $counts[$i] = $b;
  }
  $f = 0;
  asort($vals);
  foreach($vals as $key => $val){
      $f += $counts[$key];
      if($f >= $k){
          echo $val;
          break;
      }
  }