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;
namespace Solution
{
    class Solution
    {
        static void Main(string[] args)
        {
            string[] input = System.Console.ReadLine().Split(' ');
            int n = int.Parse(input[0]);
            int m = int.Parse(input[1]);
            int[] ary = new int[100001];
            for(int i = 0; i < n; i++)
            {
                input = System.Console.ReadLine().Split(' ');
                int a = int.Parse(input[0]);
                int b = int.Parse(input[1]);
                ary[a] += b;
            }
            int tmp=0,ans=0;
            for(int i = 0; i < 100001; i++)
            {
                tmp += ary[i];
                if (tmp >= m)
                {
                    ans = i;
                    break;
                }
            }
            System.Console.WriteLine(ans);
        }
    }
}