E.Umnov's chess problem, 1944. Checkmate in two moves White to play and checkmate in two moves.

[title "E.Umnov's chess problem, 1944"]
[FEN "k7/5QK1/3n1pb1/1R1p1r2/5p2/8/1p6/4R3 w KQkq - 0 1"]
1.Re4, threatening 2.Ra4#. Black has many possible moves, but all of them allow either Ra4#, Qa2# Qb7#, or Rxe8# (did I miss any?).

(In the spirit of "teaching a man to fish", if you can't solve a checkmate problem and decide to give up, you can always feed it to a chess engine and get an instant answer without having to wait for someone to reply to an online post. For example, try https://lichess.org/analysis ).