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.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace AtCoder {

    static class Program {

        static void Main() {
            var arr = Console.ReadLine().Split(' ');
            var n = int.Parse(arr[0]);
            var k = int.Parse(arr[1]);

            /*
                        var dict = new Dictionary<int, int>();
                        for (int i = 0; i < n; i++) {
                            var arr2 = ReadLine().Split(' ');
                            var a = int.Parse(arr2[0]);
                            var b = int.Parse(arr2[1]);
                            if (dict.ContainsKey(a)) {
                                dict[a] += b;
                            } else {
                                dict[a] = b;
                            }
                        }
                                    foreach (var pair in dict.OrderBy(p => p.Key)) {
                                        //    WriteLine($"before: {k}");
                                        k -= pair.Value;
                                        //  WriteLine($"after: {k}");
                                        if (k <= 0) {
                                            pair.Key.WriteLine();
                                            return;
                                        }
                                    }
                        */
        }
    }
}
/* ***************** Following Contents are my common library ******** */