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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

"use strict";
    
const main = arg => {
    arg = arg.trim().split("\n");
    const N = parseInt(arg[0].split(" ")[0]);
    const K = parseInt(arg[0].split(" ")[1]);
    const numbers = arg.slice(1, N+1);
    
    const map = [];
    
    for(let i in numbers) {
        let temp = numbers[i].split(" ").map(n=>parseInt(n));
        
        let number = temp[0];
        let amount = temp[1];
        
        map.push({number: number, amount: amount})
    }
    
    //map.sort((a,b)=>a.number - b.number);
    
    let sum = 0;
    let i   = 0;
    
    while(sum < K) {
        sum += map[i].amount;
        i++;
    }
    
    console.log(map[i - 1].number);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));