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 Fortran (gfortran v4.8.4) (judge verdict: Wrong Answer)

program main
   integer(8) N, K, i
   integer(8), allocatable :: a(:), b(:)
   read(*, *) N, K
   allocate(a(1: N))
   allocate(b(1: N))
   do i = 1, N
       read(*, *) a(i), b(i)
   end do
   do i = 1, N
       if(1 <= K .and. K <= b(i)) then
	       write(*, *) a(i)
	       exit
	   else
	       K = K - b(i)
	   end if
   end do
end program main