3 moves to checkmate

This is a puzzle that i'm trying to solve. My friend gave me this puzzle. You play white and you need to make a checkmate without stalemate in 3 moves. You cannot move your white pawn to make a promotion. Please try to figure it out, and all thanks is yours...........

Ra8, Bd8, bg5, c3, rxd8 mate, i think

O yea, if you can figure it out, please inform me... Or, you can give me suggestions.. Thanks..

One more thing..... sorry, you can't move white pawn and black pawn at all....

Ya, but i forgot to tell you that you can't move white and black pawn... sorry... good try though, thanks..

That doesn't work. After 2. Bg5, Black plays Kf8 and escapes.

I can find a mate in 4 with your restrictions, but a mate in 3 eludes me.

The idea is to get the Black bishop away from e7, but it's tricky.

(Well, I did find a way to mate in three moves, but it's definitely not forced.)

Yea, that's difficult for me too... but my friend challenged me to figure it out... thanks for the try... I appreciate it..

 i think your friend is tricking you, i anilyzed this and it seems impossible

This is impossible what ever white moves black will play Bd8 and back to e7 back and forth until we check black with the rook! Maybe an higher rating then me can solve the puzzle! a rated guy thats 2000 rating or higher can do it!

1. Ra8+  Bd8

2. Rxd8+ Kxd8

3. b8=R# UNDER-promotion!

Well, you wouldn't need to underpromote in that case.

Besides, the restrictions on the puzzle are you can't move either of the pawns ;)

1. Ra8 Bd8 2. Rxd8+ Kxd8 3. b8Q#

This is checkmate, but it doesn't fulfill the no promotion rule.

Alternatively, 1. Bf8 Bxf8 2. Ra8# is checkmate, but is not forced, and is only in three turns, not moves

To me, this seems impossible. As long as the bishop can block the rook move, it will take more than three moves.

YOUR FRIEND IS WRONG!
just kidding, i can't solve it.

b8q,bd8,qd8,kd8,ra8#

The thing is we cannot move the pawn at all.. Thanks for trying..

Does he mean 3 total moves or 3 moves for white? Here is a solution for 3 total moves:

Bf8  Bxf8

Ra8#

I got the same, only moving the bishop to g5:

Bg5 Bxg5

Ra8#

Impossible

Actually, 1. Bg5 doesn't work, because after 1. ...Bxg5 2. Ra8+, the bishop can move to d8.