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: Runtime Error)

#include <bits/stdc++.h>

#define lli long long int
#define pb push_back
#define pii pair <int, int>
#define pll pair <lli, lli>
#define _F first
#define _S second
#define mset(x) memset(x, 0, sizeof(x))
#define fastio() ios_base::sync_with_stdio(0)

using namespace std;

int main()
{
	int n, k;
	cin >> n >> k;

	int max_n = 1e5 + 5;
	int A[max_n];
	mset(A);

	while(n--)
	{
		int x, y;
		cin >> x >> y;

		A[x] += y;
	}

	for(int i=0; i<max_n; i++)
	{
		k -= A[i];

		if(k <= 0)
		{
			cout << i << endl;
			return 0;
		}
	}
	return (0-0);	
}