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: Runtime Error)

import java.util.*;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int K = sc.nextInt();
		int[] a = new int[N],b = new int[N];
		int i,k,bsum = 0;
		ArrayList<Integer> r = new ArrayList<Integer>();
		for(i = 0;i < N;i ++) {
			a[i] = sc.nextInt(); b[i] = sc.nextInt();
			for(k = 0;k < b[i];k++) {
				r.add(a[i]);
			}
		}
		
		/*for(i = 0;i < N;i ++) {
			for(k = 0;k < b[i];k++) {
				r.add(a[i]);
				//System.out.println(r);
			}
		}*/
		//System.out.println(r);
		System.out.println(r.get(K-1));
	}
	
}