Undertaker vs. John Cena in an I Quit Match at Wrestlemania, who would win?

This might be one of the most difficult question ever in this wrestling section, so let me know who you think will win and why. Remember, we are talking here about the man that never quits and is the face of the company against the man that is undefeated at WM, a WWE and wrestling legend and we cannot imagine him ever say I Quit because of his character.