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 Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.*;
import java.io.*;

public class Main{
	public static void main(String[] args)  throws IOException,NumberFormatException{
		try {
		FastScanner sc=new FastScanner();
		int n=sc.nextInt(),k=sc.nextInt();
		
		int[] count=new int[100001];
		for(int i=0;i<n;i++) {
			int a=sc.nextInt();
			int b=sc.nextInt();
			count[a]+=b;
		}
		for(int i=1;i<=100000	;i++) {
			if(k<=count[i]) {
				System.out.println(i);
				return;
			}
			k-=count[i];
		}
		}
		catch(Exception e) {
			return ;
		}
		
	}
	static final Random random=new Random();
	
	static void ruffleSort(int[] a) {
		int n=a.length;
		for(int i=0;i<n;i++) {
			int oi=random.nextInt(n),temp=a[oi];
			a[oi]=a[i]; a[i]=temp;
		}
		Arrays.sort(a);
	}
	
	public static class FastScanner {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st=new StringTokenizer("");
		String next() {
			while (!st.hasMoreTokens())
				try { 
                                      st=new StringTokenizer(br.readLine());				               
                              } catch (IOException e) {}
			return st.nextToken();
		}
		
		int nextInt() {
			return Integer.parseInt(next());
		}
		
		long nextLong() {
			return Long.parseLong(next());
		}
		
		int[] readArray(int n) {
			int[] a=new int[n];
			for (int i=0; i<n; i++) a[i]=nextInt();
			return a;
		}
		
		long[] readLongArray(int n) {
			long[] a=new long[n];
			for(int i=0; i<n ; i++) a[i]=nextLong();
			return a;
		}
		
		String nextLine() 
        { 
            String str = ""; 
            try
            { 
                str = br.readLine(); 
            } 
            catch (IOException e) 
            { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
	}

}