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>
#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
unsigned int ruio[1000001];
unsigned int ruio2[1000001];
unsigned int ruio3[1000001];

int main(){
	memset(ruio, 0, sizeof(ruio));
	memset(ruio2, 0, sizeof(ruio));
	memset(ruio3, 0, sizeof(ruio));
	unsigned int N, K;
	cin >> N >> K;
	unsigned int sum = 0;
	for (int i = 0; i < N; i++) {
		unsigned int a, b;
		cin >> a >> b;
		ruio[sum] = a;
		ruio2[sum] = b;
		if(i!=0)ruio3[sum] += ruio[sum - 1];
		for (int j = 0; j < sum; j++) {
			//if (j > K)break;
			if (ruio[j] > a) {
				for (int z = sum + b; z > j; z--) {
					ruio[z] = ruio[z - 1];
					ruio2[z] = ruio[z - 1];
				}
				ruio[j] = a;
				ruio2[j] = b;
				sum += b;
				break;
			}
		}
		sum++;
	}
	//cout << "ruio" << endl;
	/*for (int j = 0; j < N; j++) {
		for (int x = N; x > j; x--) {
			if (ruio[x - 1] > ruio[x]) {
				swap(ruio[x - 1], ruio[x]);
				swap(ruio2[x - 1], ruio2[x]);
			}
		}
	}*/
	int a, b;
	int wa = 0;
	for (int i=0;i<=sum;i++) {
		if (ruio2[i] < K) {
			K=K- ruio2[i];
		}
		else {
			cout << ruio[i] << endl;
			break;
		}
	}
}