A German student who bought a pullout couch for $215 at a Berlin flea market found a painting worth 100 times that amount hidden inside when she unfolded the sofa at home.The tiny 10- by 15-inch oil painting sold for $27,630 at a Hamburg art auction last weekend, Auction House Kunst Kettler said.The work, "Preparation to Escape to Egypt," was painted by an unknown artist close to Venetian painter Carlo Saraceni between 1605 and 1620, the auction house said Monday night.The student's identity was not revealed.