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# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;
 
class Atcoder{
   public static int[] cins() {
      string[] ss = Console.ReadLine().Split(' ');
      int[] Res = new int[ss.Length];
      for (int i = 0; i<ss.Length; i++) {
         Res[i]=int.Parse(ss[i]);
      }
      return Res;
   }
   public static void Main(string[] args) {
      int[] G = new int[100000];
      int[] k = cins();
      int N = k[0], K = k[1];
      int p=0, q=0;
      for (int i = 0; i<N; i++) {
         k=cins();
         G[k[0]-1]+=k[1];
      }

      for (int i = 0; i<100000; i++) {
         p+=G[i];
         if (p>=K) { q=i+1; break; }
      }

      Console.WriteLine(q);
   }
}