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>

long max(long a, long b){
  if(a > b) return a;
  else return b;
}

long min(long a, long b){
  if(a < b) return a;
  else return b;
}

int sort(const void *a, const void *b){
  return *(int*)a -*(int*)b;
}

int main(){

  int n,k;
  scanf("%d%d",&n,&k);

  long long int num[100001] = {0};
  for(int i = 0; i < n; ++i){
    int a,b;
    scanf("%d%d",&a,&b);
    num[a] += b;
  }

  int ans = 0;
  for(int i = 1; i <= 100000; ++i){
    if(k <= num[i]){
      printf("%d",i);
      return 0;
    }
    k -= num[i];
  }

  return 0;

}