public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        ArrayList<String> list = new ArrayList<String>();

        for(int i = 0; i < 10; i++)
            list.add(reader.readLine());

        ArrayList<String> result = doubleValues(list);

        for (String s : result)
            System.out.println(s);

    public static ArrayList<String> doubleValues(ArrayList<String> list) {
        for(int i = 0; i < list.size(); i++) {
            String a = list.get(i);
            list.add(i+1, a);
        }
        return null;
    }
illegal start of expression: Solution.java, line: 23, column: 5 illegal start of expression: Solution.java, line: 23, column: 12 ';' expected: Solution.java, line: 23, column: 28 illegal start of expression: Solution.java, line: 23, column: 37 not a statement: Solution.java, line: 23, column: 49 ';' expected: Solution.java, line: 23, column: 73 reached end of file while parsing: Solution.java, line: 29, column: 2