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: Accepted)

<?php
fscanf(STDIN, "%d %d",$n,$k);
for ($i=0; $i < $n; $i++)
	fscanf(STDIN,"%d %d",$p[$i][0],$p[$i][1]);

foreach ((array) $p as $key => $value)
    $sort[$key] = $value[0];
array_multisort($sort, SORT_ASC, $p);

for ($i=0; $i < $n; $i++)
{ 
	$k-=$p[$i][1];
	if($k<=0)
	{
		$result=$p[$i][0];
		break;
	}
}

printf("%d",$result);