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.io.*;

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    
    String[] line1 = br.readLine().split(" ");
    int n = Integer.parseInt(line1[0]);
    long k = Long.parseLong(line1[1]);
    
    
    long[] array = new long[100000];
    String[] data;
    int a;
    long b;
    for (int i=0; i<n; i++){
      data = br.readLine().split(" ");
      a = Integer.parseInt(data[0]);
      b = Integer.parseInt(data[1]);
      array[a-1] += b;
    }
    long temp = 0;
    for (int i=0; i<100000; i++){
      temp += array[i];
      if (temp>=k) {
        System.out.println(i+1);
        return;
      }
    }
  }
}