import Data.List

main = mapM_ putStrLn . solve . map read . words =<< getLine

solve :: [Int] -> [String]
solve [h,w,d] = take h $ concat [[yb], replicate d rg, replicate (d-1) yb]
    where
        yb = take w . cycle $ concat ["B", replicate d 'Y', replicate (d-1) 'B']
        rg = take w . cycle $ concat ["G", replicate d 'R', replicate (d-1) 'G']
