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 Python (2.7.6) (judge verdict: Wrong Answer)

n, k = map(lambda x: int(x), raw_input().split(" "))

d = {}
for i in range(n):
    a1, b1 = map(lambda x: int(x), raw_input().split(" "))
    #Acount += b1
    if a1 in d.keys():
        d[a1] += b1
    else:
        d[a1] = b1

#print (d)
l = sorted(d.items(), key=lambda x: x[0])
#print ("HOGEHOGE")
#print (l)
for item in l:
    if k <= item[1]:
        print item[0]
        break