Butterfly Pattern

Given an integer N, print a symmetric butterfly pattern of 2*N rows. In row i of the top half, print i stars, 2*(N - i) spaces, and i stars. The bottom half is the vertical reflection.

Input Format

A single integer N.

Output Format

Print 2*N rows forming a butterfly.

Constraints:1 <= N <= 15

Concepts Required:

Dual wing symmetryMiddle shrinking space 2*(N - i)2*N rows structure

Expected Pattern PreviewASCII Monospace

*        *
**      **
***    ***
****  ****
**********
**********
****  ****
***    ***
**      **
*        *

Notice how character spacing and row counts scale systematically based on the input N.

Concrete Examples

Example 1

Input:

Output:

*        *
**      **
***    ***
****  ****
**********
**********
****  ****
***    ***
**      **
*        *

Explanation: Top 5 rows expand wings, bottom 5 rows contract wings.

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