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 PyPy3 (2.4.0) (judge verdict: Time Limit Exceeded)

import sys
input = sys.stdin.readline

def two_int():
    N, K = map(int, input().split())
    return N,K

def one_int():
    return int(input())

def one_str():
    return input()

def many_int():
    return list(map(int, input().split()))

from collections import defaultdict


N,K = two_int()

dicts = defaultdict(int)
count = 0
for i in range(N):
    a,b = two_int()
    temp = 0
    
    for k,v in dicts.items():
        if k>a:
            dicts[k] += b
        if temp <= k <= a:
            temp = k
            
    dicts[a] = b+dicts[temp]

output = [ [k,v] for k,v in dicts.items()]

temp = sorted(output, key=lambda x: x[0])

ans=0
for i in range(len(temp)-1):
    if temp[i][1] < K <= temp[i+1][1]:
        ans=temp[i+1][0]

print(ans)