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;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Reflection;
using System.Collections.Generic;

namespace ConsoleApp1
{
    public class Program
    {
        static void Main(string[] args)
        {
            string line = Console.ReadLine();
            string[] token = line.Split(' ');
            long n = long.Parse(token[0]);
            long k = long.Parse(token[1]);
            long[] big = new long[100000];
            long index = 0;

            for (long i = 0; i < n; i++)
            {
                line = Console.ReadLine();
                token = line.Split(' ');
                long a = long.Parse(token[0]);
                long b = long.Parse(token[1]);

                for(long j = 0; j < b; j++)
                {
                    big[index++] = a;
                }
            }

            Array.Sort(big);
            Console.WriteLine(big[k+100000-index]);
        }
    }

}