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.Arrays;
import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		
		int n = stdIn.nextInt();
		int k = stdIn.nextInt();
		
		long sum = 0;
		
		int[]a = new int[n];
		int[]b = new int[n];
		
		for(int i = 0; i < n; i++) {
			a[i] = stdIn.nextInt();
			b[i] = stdIn.nextInt();
			sum += b[i];
		}
		
		int[]c = new int[(int)sum];
		int index = 0;
		
		for(int i = 0; i < n; i++) {
			int j = 0;
			while(b[i] != j) {
				c[index++] = a[i];
				j++;
			}
		}
		Arrays.sort(c);
		
		for(int i = 0; i < sum; i++) {
			if(i== k-1) {
				System.out.println(c[i]);
			}
		}
		
	}

}