Replace the question mark with a number

A drunk man who smelled like booze sat down on a bench next to a priest.The man's tie was stained, his face was plastered with red lipstick, and a half-empty bottle of gin was sticking out of his torn coat pocket. He opened his newspaper and began reading.
After a few minutes the man turned to the priest and asked,'Say Father, what causes arthritis?'
The priest replies, 'My Son, it's caused by loose living, being withcheap, wicked women, too much alcohol, contempt for your fellow man, sleeping around with prostitutes and lack of a bath.'
The drunk muttered in response, 'Well, I'll be damned,'then returned to his paper.
The priest, thinking about what he had said, nudged the manand apologized. 'I'm very sorry.
I didn't mean to come on so strong.How long have you had arthritis?
The drunk answered, 'I don't have it, Father.I was just reading here that the Pope does.