In a certain chess position, each row and each column contains an odd
number of pieces.
Prove that the total number of pieces on black squares is an even number.
Source: Proizvolov, “Problems Teaching Us How to Think".
(In reply to re: Parity Solution @Brian
by Ady TZIDON)
Done. I did not think to cross-reference the official standard. As soon as I saw it was a parity problem my focus was on the three kinds of parity (rows, columns, tiled board).