import Control.Monad
import Data.Maybe
import qualified Data.ByteString.Char8 as BS
import Data.List
import qualified Data.Vector.Unboxed as VU

readInt = fst . fromJust . BS.readInt
readIntList = map readInt . BS.words
getInt = readInt <$> BS.getLine
getIntList = readIntList <$> BS.getLine

main = do
    n <- getInt
    ls <- VU.fromList . sort <$> getIntList
    print $ sum [(binom (j+1) (n-1)  (ls VU.! i) (ls VU.! j) ls) - j | i <- [0..(n-3)], j <- [(i+1)..(n-2)]]

binom m1 m2 a b ls | m1 == m2 && tri a b (ls VU.! m1) = m1
                   | m1 == m2 = m1 - 1
                   | tri a b c = binom m' m2 a b ls
                   | otherwise = binom m1 (m' - 1) a b ls
    where m' = (m1 + m2) `div` 2 + 1
          c = ls VU.! m'

tri a b c | a + b > c && b + c > a && c + a > b = True
          | otherwise = False
