One flew over the cuckoo's nest

A few time ago, I see the name of the movie very attractive "One flew over the cuckoo's nest". And  I ask myself: What kind of movie can be called like that? What genre is the movie? What kind of topics speak about? 

The only thing I now about the movie is that was starring by Jack Nicholson and for that reazon the movie must be good, and It' was! 

The movie  won a Oscar in 1975 and is a great classic in history of  North American cinema.  It's a dramma film, directed by Milos Forman.

The history beggins when Mac McMurphy( Jack Nicholson) gets in a mental institution. MacMurphy is a prisoner who pretends to be crazy only for scape to jail, and stays for a long time receiving a treatment for his behavior.

MacMurphy changes all the structure in the institution,he turns the hospital in a place for fun and bet. For that reazon MacMurphy becomes in a new leader for all the crazy mans. MacMurphy try that all the sick mans who stay in hospital enjoy life for first time in their lives.  

Also, MacMurphy meets a friend in the institution who stays in there for his own will. The Chief Bromden (Will Sampson).At the end Chief and MacMurphy plans run away from there to live in Canada. 

But Doctor's Knows what McMurphy really are, and they give him the worst treatment: "the lobotomy", that changes MacMurphy life forever.