Five in a row problem #510

The task

To move

Dark

Difficulty

Easy

Goal

win in 2

10 stones are already on the lattice. Two moves: make a four that also creates a second threat.

What to look for

• Continuous fours: each move forces an immediate block.
• An open four appears, and it cannot be stopped.

How the answer is checked

There is exactly one first move that forces the result; any other first move allows the defence to escape. Moves that keep the forced result are accepted later in the line, and a move that loses it is taken back with a short note.