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 C# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;
using System.Collections.Generic;

class Program
{
	static void Main(string[] args)
	{
		int maxInsTime, minRank;
		string[] vals = Console.ReadLine().Split(' ');
		maxInsTime = int.Parse(vals[0]);
		minRank = int.Parse(vals[1]);
		
		List<int> intList = new List<int>();
 
		int[] insNum = new int[maxInsTime];
		int[] insTime = new int[maxInsTime];
		for(int i=0; i < maxInsTime; i++)
		{
			vals = Console.ReadLine().Split(' ');
			insNum[i] = int.Parse(vals[0]);
			insTime[i] = int.Parse(vals[1]);
			
			for(int j = 0; j < insTime[i]; j++){
				intList.Add(insNum[i]);
			}
		}
		
		intList.Sort();

		Console.WriteLine(intList[minRank - 1]);
	}
}