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.Linq;
using System.Collections.Generic;
public class Hello{
    public static void Main(){
        var line = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        var list = new List<int>();
        var N = line[0];
        var K = line[1];
        
        for(var i = 0;i < N;i++){
            line = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            var a = line[0];
            var b = line[1];
            
            for(var j = 0;j < b;j++){
                list.Add(a);
            }
        }
        Console.WriteLine(list[K - 1]);
    }
}