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: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define FOR(i ,a, b) for (int i = a ; i <= b ; i++)
#define sz(a) int(a.size())
#define cuti(a) cout << a << endl;
#define cutii(a,b) cout << a << " " << b << endl;
#define vec(a) vector<int > a;

template<typename T,typename U> inline void chmin(T &x,U y){ if(y<x) x = y; }

typedef pair<int ,int > pii;
typedef long long LL;
const long long oo = 1e9 + 7;

int n;
long long k;

int main() {
 //   freopen("test.txt","r",stdin);
    cin >> n >> k;
    long long now = 0;
    for (int  i =1 ; i <= n ; i++) {
        int x , y ;
        cin >> x >> y;
        now += y ;
        if ( now >= k ) {
            cuti(x);
            return 0;
        }
    }
}