main = getContents >>= mapM_ (putStrLn . national_budget) . reverse . fin [] . tail . lines
fin acc [] = acc
fin acc (x:y:xys) = fin ([x,y]:acc) xys

national_budget [x,y]
 | (length x > 80) || (length y > 80) = "overflow"
 | (length $ show (read x + read y)) > 80 = "overflow"
 | otherwise = show (read x + read y)