Black-and-white cube#4647
You are given a cube with dimensions k \times k \times k, composed of unit cubes. Two unit cubes are considered adjacent if they share a face.
Your task is to color each of the k^3 unit cubes using one of two colors: black or white. The coloring must satisfy the following conditions:
Each white cube must have exactly adjacent cubes that are also white.
Each black cube must have exactly adjacent cubes that are also black.
The input consists of a single integer (1 \leq k \leq 100) — the size of the cube.
If no valid coloring exists, output -1. Otherwise, provide the coloring of the cube layer by layer. For the first lines, output the k \times k matrix representing the first layer of the cube. For the next lines, output the k \times k matrix for the second layer, and continue in this manner until the -th and final layer.
Use the symbol "w" to denote a white unit cube and "b" for a black unit cube. Follow the output format as demonstrated in the test examples.
Example 1