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: Accepted)

#include<stdio.h>
 
int main(){
   int n;
  long long int k;
  scanf("%d%lld",&n,&k);
 
  long long int num[100001] = {0};
  for(int i = 1; i <=n; i++){
    int a,b;
    scanf("%d%d",&a,&b);
    num[a] += b;
  }
  for(int i = 1; i <= 100000; ++i){
    k = k-num[i];
    if( k <= 0 ){
      printf("%d",i);
      return 0;
    }
  }
 
  return 0;
 
}