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>
int int_sort( const void * a , const void * b ) {
  if( *( long long int * )a < *( long long int * )b ) {
    return -1;
  }
  else
  if( *( long long int * )a == *(long long  int * )b ) {
    return 0;
  }
  return 1;
}

int main(void){
    int N,K;
    scanf("%d %d",&N,&K);
    long long int a[114514]={};
      size_t data_cnt=sizeof( a )/sizeof( a[0] );
    for(int i=0;i<114514;i++)a[i]=2000000000000;
    for(int i=0;i<N;i++){
        int s,t;
        scanf("%d %d",&s,&t);
        a[i]=1000000*s+t;
    }
      qsort(( void * )a, data_cnt , sizeof( a[0] )   , int_sort );
      int count=0;
      for(int i=0;i<N;i++){
          count+=a[i]%1000000;
          if(count>=K){
              printf("%lld",a[i]/1000000);
              break;
          }
      }
    
    return 0;
}