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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

int main()
{
	int n, k, i;
	long long int cou = 0;
	scanf("%d %d", &n, &k);

	int *a = (int*)malloc(n * sizeof(int));
	int *b = (int*)malloc(n * sizeof(int));
	long long int c[100000];

	for (i = 0; i <=99999; i++) {
		c[i] = 0;
	}
	for (i = 0; i < n; i++) {
		scanf("%d %d", &a[i], &b[i]);
	}

	for (i = 0; i < n; i++) {
		c[a[i] - 1] += b[i];
	}
	for (i = 0; i <=99999;i++) {
		cou += c[i];
		
		if(cou>=k) {
			printf("%d\n", i + 1);
			break;
		}
	}
	free(a);
	free(b);
	return 0;
	
}