What is wrong with this position?

What is wrong with the following position?

Budapest 1921
Sterk, Karoly

Alekhine, Alexander
(After 8...O-O)
[FEN "r1bq1rk1/pp1nbppp/2p1pn2/3p4/2PP4/2N1PN2/PPQ2PPP/R1B1KB1R w KQ - 0 9"]

Hint: Consider the last move, then count the moves made by both players. To play through the complete game see...

Alexander Alekhine vs Karoly Sterk, Budapest 1921
http://www.chessgames.com/perl/chessgame?gid=1012053

...on Chessgames.com.