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.util.Scanner;

public class Main {

	@SuppressWarnings("resource")
	public static void main(String args[]) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		long k = scanner.nextLong();
		int a[] =new int[100000];
		int b[] =new int[100000];
		boolean judge=true;
		int ans=0;
		
		long bSum=0;
		for(int i=0;i<n;i++){
			a[i]=scanner.nextInt();
			b[i]=scanner.nextInt();
			if(i!=0&&a[i]<a[i-1]){
				int tmp=0;
				tmp=a[i-1];
				a[i-1]=a[i];
				a[i]=tmp;
				tmp=b[i-1];
				b[i-1]=b[i];
				b[i]=tmp;
			}
			
		}
		
		for(int i=0;i<n;i++){
			bSum+=b[i];
			if(bSum>=k&&judge){
				judge=false;
				ans=a[i];
			}
		}

		System.out.println(ans);
	}
}