Task: Question Answering
Input (English): In a positive review of the song, Robert Copsey of Digital Spy gave it four out of five stars and praised Rihanna's direction towards a "softer and more prolific edge". Brittany Lewis of GlobalGrind called "Diamonds" a catchy song and felt that it had the potential to be another hit for Rihanna. Glenn Gamboa of Newsday said that, although it does not sound like an emphatic hit, the lyrical content of the song depicts a "personal shift" for Rihanna. According to James Montgomery of MTV News, "Diamonds" is more positive than previous singles such as "We Found Love" and "Where Have You Been", despite its moderate tempo. Lindsey DiMattina of Hollywood.com said that Rihanna's singing is stronger than ever. Contactmusic's reviewer described it as a "laid-back track", and suggested that the lyrical content is related to her former boyfriend Chris Brown. In a track-by-track review of Unapologetic, Andrew Hampp of Billboard found the song inspiring and commented that it "finds Rihanna doing one of her throatiest, most impassioned vocals to date". Andy Kellman of Allmusic cited the song as one of the highlights on Unapologetic, and gave it three and a half stars.In a less enthusiastic critique, Jon Caramanica of The New York Times likened "Diamonds" to a James Bond movie theme song, but with "insipid lyrics". Jim Farber of the New York Daily News felt that the song is not as evocative as it attempts to be and lacks the sense of mystery and engaging production found on "We Found Love". Kevin Blair of the Irish Independent's, Independent Woman, was critical of the song for deviating from Rihanna's previous dance and R&B songs and dismissed it as a "chugging, faintly misty-eyed, middle of the road pop song". Chris Richards of The Washington Post panned the song as a "power ballad without much power". 
Question: What is the name of the person whose former boyfriend is suggested by Contactmusic's reviewer to be related to the lyrical content of Diamonds?
Output (English): Rihanna