bool expressionFound(istringstream &ss, Node &root)
{
    int leaves;
    char op;
    if (ss.peek() >= 48 && ss.peek() <= 71)
    {
        root.tag = INT_ONLY;
        ss >> leaves;
        root.intValue = leaves;
    }
    else if (ss.peek() == '(')
    {
        root.left = new Node;
        expressionFound(ss, *root.left);
        ss >> op;
        root.tag = SUB_NODE;
        root.op = op;
        root.right = new Node;
        if (expressionFound(ss, *root.right))
        {
            if (ss.peek() == ')')
            {
                ss >> op;
            }
        }
    }
    return false;
}