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 {
	
	static int sum(int a[]){
		int sum = 0;
		for(int i = 0; i < a.length; i++)
			sum += a[i];
		
		return sum;
	}
 
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt(), k = sc.nextInt();
		
		int a[] = new int[n], b[] = new int[n];
		for(int i = 0; i < n; i++){
			a[i] = sc.nextInt();
			b[i] = sc.nextInt();
		}
		
		int bigArray[] = new int[sum(b)];
		int bigIndex = 0;
		for(int i = 0; i < n; i++)
			for(int j = 0; j < b[i]; j++)
				bigArray[bigIndex++] = a[i];
		
		Arrays.sort(bigArray);
		
		System.out.println(bigArray[3]);
		
	}
 
}