Problem Statement

Two segments [L_1:R_1] and [L_2:R_2] are said to intersect when $L_1 \leq R_2$ and $L_2 \leq R_1$ holds.
Consider the following problem P:
Input: N segments [L_1: $R_1], \cdots, [L_N$:R_N]
$L_1, L_2, \cdots, L_N, R_1, R_2, \cdots, R_N$ are pairwise distinct.
Output: the maximum number of segments that can be chosen so that no two of them intersect.

Takahashi has implemented a program that works as follows:
Sort the given segments in the increasing order of R_i and let the result be [L_{p_1}:R_{p_1}], [L_{p_2}:$R_{p_2}], \cdots , [L_{p_N}$:R_{p_N}].
For each $i = 1, 2, \cdots , N,$ do the following:
Choose [L_{p_i}:R_{p_i}] if it intersects with none of the segments chosen so far.
Print the number of chosen segments.

Aoki, on the other hand, has implemented a program that works as follows:
Sort the given segments in the increasing order of L_i and let the result be [L_{p_1}:R_{p_1}], [L_{p_2}:$R_{p_2}], \cdots , [L_{p_N}$:R_{p_N}].
For each $i = 1, 2, \cdots , N,$ do the following:
Choose [L_{p_i}:R_{p_i}] if it intersects with none of the segments chosen so far.
Print the number of chosen segments.

Given are integers N and M. Construct an input for the problem P, consisting of N segments, such that the following holds:
$$ (\text{The value printed by Takahashi's program}) - (\text{The value printed by Aoki's program}) = M $$

Input

Input is given from Standard Input in the following format:
N M

Output

If there is no set of N segments that satisfies the condition, print -1.
Otherwise, print N lines as follows:
L_1 R_1
L_2 R_2
$\vdots$
L_N R_N

Here, [L_1:$R_1], \cdots, [L_N$:R_N] must satisfy the following:

• $1 \leq L_i < R_i \leq 10^9$
• $L_i \neq L_j (i \neq j)$
• $R_i \neq R_j (i \neq j)$
• $L_i \neq R_j$
• $L_1, \cdots , L_N , R_1, \cdots , R_N$ are integers (21:46 added)

If there are multiple answers, any of them will be accepted.
Be sure to print a newline at the end of the output.

Constraints

• All values in input are integers.
• $1 \leq N \leq 2 \times 10^5$
• -$N \leq M \leq N$

Sample Input 1

5 1

Sample Output 1

1 10
8 12
13 20
11 14
2 4

Let us call the five segments Segment $1, Segment 2, \cdots, Segment 5$.
Takahashi's program will work as follows:
Rearrange the segments into the order Segment 5, Segment 1, Segment 2, Segment 4, Segment 3.
Choose Segment 5.
Skip Segment 1 (because it intersects with Segment 5).
Choose Segment 2.
Skip Segment 4 (because it intersects with Segment 2).
Choose Segment 3.

Thus, Takahashi's program will print 3.
Aoki's program will work as follows:
Rearrange the segments into the order Segment 1, Segment 5, Segment 2, Segment 4, Segment 3.
Choose Segment 1.
Skip Segment 5 (because it intersects with Segment 1).
Skip Segment 2 (because it intersects with Segment 1).
Choose Segment 4.
Skip Segment 3 (because it intersects with Segment 4).

Thus, Aoki's program will print 2.
Here, we have $3 - 2 = 1 \left(= M \right)$, and thus these five segments satisfy the condition.

Sample Input 2

10 -10

Sample Output 2

-1

见题面 Input 部分

见题面 Output 部分