[FEN "6k1/R7/P6p/7N/3Pp1P1/4P1B1/5PPK/r4b2 w -"]

39. Nf6+ Kf8 40. Bd6#


w b wb bw | w b wb bw

w     an



39. Nf6+      an



39...Kf8      an



40. Bd6#      an