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 static System.Console;
using static System.Math;

public class Hello{
    public static void Main(){
        string[] kosuans = ReadLine().Split(' ');
        int kosu = int.Parse(kosuans[0]);
        int ans = int.Parse(kosuans[1]);
        int[] count = new int[110000];
        for(int i=0;i<kosu;i++){
            string[] temp = ReadLine().Split(' ');
            int a = int.Parse(temp[0]);
            int b = int.Parse(temp[1]);
            count[a] += b;
        }
        int check = 0;
        for(int i=1;i<=100000;i++){
            check += count[i];
            if(check >= ans){
                WriteLine(i);
                break;
            }
        }
    }
}