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;
using System.Linq;
using static System.Console;
using static System.Convert;
using static System.Math;

class Program
{
    static void Main(string[] args)
    {
        var input = ReadLine().Split(' ');
        var num = ToInt32(input[0]);
        var fig = ToInt32(input[1]);
        var arr = new long[num, 2];
        long sum = 0;
        for (var i = 0; i < num; i++)
        {
            var inp = ReadLine().Split(' ');
            arr[i, 0] = ToInt64(inp[0]);
            arr[i, 1] = ToInt64(inp[1]);
        }
        for(var i = 0; i < num; i++) { 
            sum += arr[i,1];
            if (sum >= fig) { WriteLine(arr[i,0]);return; }
        }
    }
}