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 <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
typedef struct two{
	int num;
	int time;	
}Do;
bool cmp(Do x, Do y)
{
	if(x.num < y.num)
		return 1;
	return 0;
}
int main()
{
	Do a[100005];
	int n, k, i;
	cin>>n>>k;
	for(i = 0; i < n; i++)
		cin>>a[i].num>>a[i].time;
	sort(a, a + n, cmp);
	//cout<<a[0].num<<endl;
	//cout<<a[9].num<<endl;
	for(i = 0; i < n;i++)
	{
		//cout<<k<<endl;
	//	cout<<a[i].num<<endl;
		if(k - a[i].time <= 0)
		{
			cout<<a[i].num;
			break;
		}
		k = k - a[i].time;
	}
	return 0;
}