Series helpmate in 3

A. Storisteanu
Buletin Problemistic 1996

Series helpmate in 3
2 solutions
(Series helpmate: Black plays n moves in a row, then White gives checkmate with a single move.)

Originally posted by BigDoggProblem
A. Storisteanu
Buletin Problemistic 1996
[fen]8/8/8/8/8/4N3/2p1K3/Q4N1k[/fen]
Series helpmate in 3
2 solutions
(Series helpmate: Black plays n moves in a row, then White gives checkmate with a single move.)

Originally posted by Mephisto2
a)
c1=R
Rxf1
Rg1 Qh8#

b)
c1=B
Bxe3
Bg1 Qa8#