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;

namespace ConsoleApplication1
{

    class Program
    {

        static void Main(string[] args)
        {


            string[] str = Console.ReadLine().Split(' ');

            int n = int.Parse(str[0]);
            int k = int.Parse(str[1]);

            var list = new SortedDictionary<int, int>();

            for(int i = 0; i < n; i++)
            {
                string[] strer = Console.ReadLine().Split(' ');
                int key = int.Parse(strer[0]);
                int vla = int.Parse(strer[1]);
                if (list.ContainsKey(key))
                {
                    list[key] += vla;
                }
                else
                {
                    list[key] = vla;
                }
                
            }
            
            int u = 0;
            
            foreach(var s in list)
            {
                u = s.Value;
                if(u >= k)
                {
                    Console.WriteLine(s.Key);
                    break;
                }
                else
                {
                    k -= u;
                }

            }


        }
    }
}