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++14 (GCC 5.4.1) (judge verdict: Accepted)

#define __USE_MINGW_ANSI_STDIO 0
#include <iostream>
#include <string>
#include <vector>
#include <stdio.h>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <set>
#include <numeric>
#include <bitset>
#include <map>
#include <limits.h>
using namespace std;
typedef unsigned long ul;
typedef pair<ul, ul> P;
const int INF = 1e9;




int main(){
    int N;
    long long K;
    cin >> N >> K;
    long long ans[100000+1] = {};
    for(int i = 0; i < N;i++){
        int a,b;
        cin >> a >> b;
        ans[a] += b;
    }
    for(int i = 1; i <= 100000;i++){
        if(ans[i]>= K){
            cout << i << endl;
            break;
        }
     K -=ans[i];
    }
return 0;

}