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 Perl (v5.18.2) (judge verdict: Wrong Answer)

my $N = 0;
my $K = 0;
 
my $input_string = <STDIN>;
 
($N, $K) = split(/ /, $input_string);
 
my @input_count = ();
 
for(my $i = 0; $i < $N; $i++){
	push(@input_count, 0);
}
 
my @array = ();
for(my $i = 0; $i <= $N; $i++){
	$array[$i] = 0;
}


my $aa = 0;
my $bb = 0;

until($input_count[-1] == 1){
	my $row_ab = <STDIN>;
 
	chomp($row_ab);

	($aa, $bb) = split(/ /, $row_ab);

	$array[$aa] += $bb;
	
	$input_count[$j] = 1;
	$j++;
}

my $th = 0;
my $i = 0;
for($i = 1; $i <= $N; $i++){
	$th += $array[$i];
	
	if($th >= $K){
		last;
	}
}

print "$i\n";