A problem of nimble manoeuvres leading up to a simple but elegant checkmate - it is White to play. Find the key move.

1. Ree6 Kc4 - Black has escaped the threat of Rc6#. How should White continue?

2. Rg3 Kc5 - Once again Black escapes the threat of Rc6#. How should White proceed?

3. Rd3 Kc4 - White to play. What's White's best move now?

4. Rf3 Kc5 - How should White proceed?

5. Rf4 f1=Q - Final move? White to play.