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) {
		new Main().solve();
	}
	int n,k;
	void solve(){
		Scanner sc=new Scanner(System.in);
		n=sc.nextInt();
		k=sc.nextInt();
		int[]a=new int[n];
		int[]b=new int[n];
		Pair[] p=new Pair[n];
		for(int i=0;i<n;i++){
			a[i]=sc.nextInt();
			b[i]=sc.nextInt();
			p[i]=new Pair(a[i],b[i]);
		}
		Arrays.sort(p);
		for(int i=0;i<n;i++){
			k-=p[i].b;
			if(k>0)continue;
			else{
				System.out.println(p[i].a);
				return;
			}
		}
	}
	class Pair implements Comparable<Pair>{
		int a;
		int b;
		Pair(int a,int b){
			this.a=a;
			this.b=b;
		}
		
		public int compareTo(Pair o){
			return this.a-o.a;
		}
	}
}