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: Runtime Error)

#include <stdio.h>

int main(int argc, char const *argv[]) {
  int n=0,k=0;
  scanf("%d %d",&n,&k);
  int retu[k];

  for (size_t i = 0; i < k; i++) {
    retu[i]=1000000;
  }

  for (size_t i = 0; i < n; i++) {
    int a=0,b=0;
    scanf("%d %d",&a,&b);

    if(a<retu[k-1]){
      for (size_t j = 0; j < k; j++) {
        if(retu[j]>=a){
          for (size_t z = j; z < k; z++) {
            retu[z+b]=retu[z];
            retu[z]=a;
          }
          break;
        }
      }
    }

  }

  printf("%d\n",retu[k-1]);
  return 0;
}