If there are more than one elements , then recur for left and right subtrees and store the sum of the two values in this node
mid = getMid ( ss , se ) NEW_LINE st [ si ] = constructSTUtil ( arr , ss , mid , st , si * 2 + 1 , isPrime ) + constructSTUtil ( arr , mid + 1 , se , st , si * 2 + 2 , isPrime ) NEW_LINE return st [ si ] NEW_LINE