A modern exercise?

There are only a few mansubat that have only `modern' pieces and rules: most have some elephant or generals playing a role. This problem does not have these old pieces (which were replaced by bishops and queens), and is also not affected by other differences between Shatranj and usual (FIDE) chess. One can still imagine to find this problem published as a simple modern chess exercise.

White:
King g7; Rook a2, d2; Knight c3. (4 pieces).

Black:
King c1; Roof f6, h6; Knight e5. (4 pieces).

Black to play and win.

Solution