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.*;

public class Main {
	
	class C implements Comparable<C>{
		public int a,b;
		
		public C(int a, int b) {
			super();
			this.a = a;
			this.b = b;
		}

		@Override
		public int compareTo(C o) {
			if(this.a < o.a) return -1;
			if(this.a > this.b)return 1;
			return 0;
		}

		@Override
		public String toString() {
			return "C [a=" + a + ", b=" + b + "]";
		}
		
	}
	
	private void doit(){
		Scanner sc = new Scanner(System.in);
//		while(sc.hasNext()){
			int n = sc.nextInt();
			int k = sc.nextInt();
			
			ArrayList<C> data = new ArrayList<>();
			for(int i =0 ; i < n;i++){
				int a = sc.nextInt();
				int b = sc.nextInt();
				C c = new C(a, b);
				data.add(c);
			}
			Collections.sort(data);
			
			long sum = 0;
			for(C c: data){
				sum += c.b;
				if(sum >= k){
					System.out.println(c.a);
					break;
				}
			}
//		}
	}

	private void debug(Object... o) {
		System.out.println("debug = " + Arrays.deepToString(o));
	}

	public static void main(String[] args) {
		new Main().doit();
	}

}