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 Java7 (OpenJDK 1.7.0) (judge verdict: Runtime Error)

import java.util.LinkedHashMap;
import java.util.Scanner;
import java.util.TreeMap;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();

		long c,d;


		LinkedHashMap<Long, Long> map = new LinkedHashMap<Long, Long>();
		for(int i = 0; i < a; i++) {
			c = sc.nextLong();
			d = sc.nextLong();
			if(map.get(c) != null) {
				map.put(c, map.get(c) + d);
			} else {
				map.put(c, d);
			}
		}

		TreeMap<Integer, Integer> treeMap = new TreeMap(map);//[10]

		for (long key : treeMap.keySet()) {//[8]
            if(map.get(key) >= b) {
            	System.out.println(key);
            	break;
            } else {
            	b -= map.get(key);
            }
        }

	}

}