import Data.Array
import Data.List

main = do
    n <- read <$> getLine :: IO Int
    ms <- map read . words <$> getLine :: IO [Int]
    let ns = listArray (1,n) ms :: Array Int Int
    let s = sum ms
    putStrLn $ if mod s 2 == 0 && dp ns (div s 2) 
        then "possible" else "impossible"


dp :: Array Int Int -> Int -> Bool
dp ns half = memo!(n,half)
    where
    (_,n) = bounds ns
    memo = array ((0,0), (n,10000)) [((y,x), f y x)|y<-[0..n], x<-[0..10000]]
    f 0 0 = True
    f 0 x = False
    f y x = memo!(y-1,x) || (if x-(ns!y)>=0 then memo!(y-1,x-(ns!y)) else False)