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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

//#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <algorithm>

#include <climits>
#include <cmath>
#include <cstring>

#include <iomanip>

using namespace std;

#define FAST       			ios_base :: sync_with_stdio(false); cin.tie(NULL); 
#define endl "\n"

typedef long long int  ll;
typedef unsigned long long int ull;


int main()
{
	FAST;
	ll arr[100002] = {};
	int n,k;
	cin >> n >> k;
	for(int i=0 ; i<n ; i++)
	{
		int a,b;
		cin >> a >> b;
		arr[a] += b;
	}

	for(int i=0 ; i<=n ; i++)
	{
		if(arr[i] > 0)
		{
			if(k-arr[i] <= 0)
			{
				cout << i; return 0;
			}
			k -= arr[i];
		}
	}
	return 0;
}