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;

namespace ConsoleApplication6
{
    class Program
    {
        static void Main(string[] args)
        {
            var split = Console.ReadLine().Split(' ');
            int N = Int32.Parse(split[0]);
            int K = Int32.Parse(split[1]);
            int[][] pair = new int[N][];
            for (int c = 0; c < N; c++)
            {
                split = Console.ReadLine().Split(' ');
                int a = Int32.Parse(split[0]);
                int b = Int32.Parse(split[1]);
                pair[c] = new int[2];
                pair[c][0] = a;
                pair[c][1] = b;
            }
            Array.Sort(pair, compare);
            int sum = 0;
            int outcounter = 0;
            for (int c = 0; sum < K;c++)
            {
                sum += pair[c][1];
                outcounter = c;

            }
            Console.WriteLine(pair[outcounter][0]);
        }

        public static int compare(int[] x, int[] y)
        {
            if (x[0] > y[0])
                return 1;
            if (x[0] < y[0])
                return -1;
            else return 0;
        }
    }
}