-- getInt function
-- Reads a line from standard in and transforms it to integer.
getInt :: IO Int
getInt = do
            line <- getLine
            return (read line :: Int)

-- sI function
-- Takes an integer as parameter, reads another integer, and sums the two.
-- Continues until 0 is input.
sI:: Int -> IO Int
sI s = do
        n<-getInt
        if n==0
            then return s
        else sI (s+n)