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: Wrong Answer)

using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;

namespace CSharp_Shell
{

    public static class Program 
    {
        public static void Main() 
        {
            var inputs1=Console.ReadLine().Split();
            var n=int.Parse(inputs1[0]);
            var k=long.Parse(inputs1[1]);
           
            var bSum=0L;
            for(var i=0;i<n;i++)
            {
           	     var inputs2=Console.ReadLine().Split();
           	     var a=int.Parse(inputs2[0]);
           	     var b=int.Parse(inputs2[1]);
           	     bSum+=b;
           	     if(bSum>=k)
           	     {
           	         Console.WriteLine(a);
           	         break;
           	     }
            }
        }
    }
}