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;
using System.Linq;
using System.Text;
 
	class _062A
    {
        static void Main()
        {
            var arr = Console.ReadLine().Split().Select(int.Parse).ToArray();
			
			List<numbers> list = new List<numbers>();
			for(var i = 0; i < arr[0]; i++)
			{
				var x = new numbers();
				var arr2 = Console.ReadLine().Split().Select(int.Parse).ToArray();
				x.a = arr2[0];
				x.b = arr2[1];
				list.Add(x);
			}
			
			list.OrderBy(x => x.a);
			
			var point = 0;
			var output = 0;
			foreach(var y in list)
			{
				output = y.a;
				point += y.b;
				if (point >= arr[1])
					break;
			}
			Console.WriteLine(output);
        }
		
		public class numbers
		{
			public int a{get; set;}
			public int b{get; set;}
		}
		
    }