sentences:  The group's debut album, "PCD", was released in September 2005 and sold three million copies in the United States.The album's lead single, "Don't Cha", was a number-one hit in various countries worldwide, and reaching number two on the US "Billboard" Hot 100.It was followed by "Stickwitu", which became their second number-one single in the UK and New Zealand, and reached number five on the Hot 100.