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 Java7 (OpenJDK 1.7.0) (judge verdict: Runtime Error)

import java.io.BufferedReader;
import java.io.InputStreamReader;

class Main{

	public static void main(String[] args) throws Exception {
       BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
       String[] input = br.readLine().split(" ");
       int n = Integer.parseInt(input[0]);
       int k = Integer.parseInt(input[1]);
       int[] a = new int[n];
       int[] b = new int[n];
       for(int i = 0;i < n;i++){
       	input = br.readLine().split(" ");
       	a[i] = Integer.parseInt(input[0]);
       	b[i] = Integer.parseInt(input[1]);
       }
       int l = 0;
       int m = 0;
       while(m < k){
       	if(b[l] > 0){
       		b[l] -= 1;
       	}
       	if(b[l] <= 0){
       		l += 1;
       	}
       	m += 1;
       }
       System.out.println(a[l]);
   }

}