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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)


import java.io.PrintWriter;
import java.util.*;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		int N = Integer.parseInt(sc.next());
		long K = Long.parseLong(sc.next());
		ArrayList<Integer> list = new ArrayList<Integer>();
		for(int i=0 ; i<100000 ; i++){
			list.add(-0);
		}
		for(int i=0;i<N;i++){
			Integer a = sc.nextInt();
			Integer b = sc.nextInt();
			if(list.get(a-1) == 0){
				list.set(a-1,b);
			}
			else{
				int tmp = list.get(a-1);
				list.set(a-1,tmp+b);
			}
		}
		int result = 0;
		for(int i=0;i<100000;i++) {
			if(K<=0){
				result = i;
				break;
			}
			K-=list.get(i);
		}
		out.println(result);

	sc.close();
	out.flush();
	}
}