West also surveys and analyzes lyrical trends in the continuously evolving landscape of hip hop culture, often changing his approach to rhyming couplets for his songwriting and delivery. Lyrically, West's wordplay generally contains a proliferation of puns and inventive, multi-syllabic rhymes. Both his songwriting and vocal delivery rely on lines laden with transformative and slant rhymes, with West, often altering the pronunciation of his words. West admits his rapping ability is not as dexterous as peers Jay-Z, Eminem and Nas, so he compensates with the subject matter. He elaborates, "the songs offer melody and message. That's the main goal. I saw it as a simple math project: If I can rap 70 to 80 percent as good as the beats are, I'll be successful." West drew influence from mainstream rappers such as Mase and his Roc-A-Fella labelmates Jay-Z and Cam'ron in conjunction with underground hip hop artists like Mos Def, Talib Kweli and Dead Prez. Kanye stated that Dead Prez in particular helped him discover a style of making "raps with a message sound cool."