B pro

B proB proB proB pro
B proB proB proB proB proB proB proB pro
B proB proB proB proB proB proB proB proB proB proB proB pro
B proB proB proB proB proB proB proB proB proB proB proB proB proB proB proB pro
B proB proB proB proB proB proB proB pro