md5_hash("hello_world",12,"5369b6a149a6a5c009df28a57c3aab24").
md5_valid("hello_world",12,"5369b6a149a6a5c009df28a57c3aab24",X) :-
  md5_check("hello",6,"0f7220a0df94ad88e497ae2fa6c56cdd",X),
  md5_check("world",6,"0f7220a0df94ad88e497ae2fa6c56cdd",X).