Chess Square Color

Use a board whose top-left square is white. Rows and columns start at 0 at the top left. Adjacent squares alternate colors. Return empty text for a position outside the board.

Implement chess_square_color(column, row).

Input

column: The column, counted from the left starting at 0.

row: The row, counted from the top starting at 0.

Output

Return white, black, or an empty string for invalid coordinates.

Vincoli

−10 ≤ column, row ≤ 20. Valid board coordinates are 0 through 7.

Esempi

Input:
row = 3
column = 2

Output atteso:
expected = "black"

Input:
long long row = 3;
long long column = 2;

Output atteso:
std::string expected = "black";

Input:
long row = 3;
long column = 2;

Output atteso:
string expected = "black";

Input:
row = 0
column = 8

Output atteso:
expected = ""

Input:
long long row = 0;
long long column = 8;

Output atteso:
std::string expected = "";

Input:
long row = 0;
long column = 8;

Output atteso:
string expected = "";

Riferimenti

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• #9 Chess Square Color