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: Accepted)



import java.util.HashMap;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		long k = sc.nextLong();

		HashMap<Integer, Long> map = new HashMap<Integer, Long>();
		for(int i = 0; i < n; i++){
			int a = sc.nextInt();
			int b = sc.nextInt();

			if(!map.containsKey(a)){
				map.put(a, (long)b);
			}
			else {
				map.put(a, map.get(a) + b);
			}
		}

		for(int i = 1; i <= 100000; i++){
			if(!map.containsKey(i)){
				continue;
			}
			k -= map.get(i);

			if(k <= 0){
				System.out.println(i);
				break;
			}
		}
	}
}