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: Runtime Error)

#define _USE_MATH_DEFINES
#include <sstream> //string stream its useful!
#include<string>
#include<iostream>
#include<utility> //pair
#include <vector> // vector
#include <algorithm>    // swap,sort,binary_search
#include <functional>   // std::greater
#include <map> //map
#include<set> //set
#include<queue> //queue
#include<list> //list
#include<cmath>
#include<numeric>
#include<cassert>
#include <iomanip> //cout<<setprecision
#include <regex>



typedef long long ll;
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
ll W = 1000000007;


using namespace std;
void omajinai() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout<<setprecision(15);
    //freopen("txt.csv","r",stdin);
}


class Main{
public:
    Main(){
        
    }
    
    
    void run(){
        vector<int> X(100001,0);
        int N; ll K; cin>>N>>K;
        REP(i,N){
            int a, b; cin>>a>>b;
            X[a]+=b;
        }
        int ans = 0;
        while(K>0){
            ans++;
            K-=X[ans];
        }
        cout<<ans<<endl;
    }
};

int main(){
    omajinai();
    Main().run();
}