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) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan = new Scanner(System.in);
        int N = scan.nextInt();
        long K = scan.nextInt();
        int [] A = new int [N];
        int [] B = new int [N];
        long sum = 0;
        for(int i=0;i<N;i++){
        	A[i] = scan.nextInt();
        	B[i] = scan.nextInt();
        }
        for(int i=0;i<N;i++){
        	for(int j=i+1;j<N;j++){
        		if(A[i]>A[j]){
        			int temp =A[i];
        			int temps =B[i];
        			A[i]=A[j];
        			B[i]=B[j];
        			A[j]=temp;
        			B[j]=temps;
        		}
        	}
        }
        for(int i=0;i<N;i++){
        	sum +=B[i];
        	if(sum>=K){
        		System.out.println(A[i]);
        		break;
        	}
        }
	}

}