import java.io.*;

class PushbackReaderDemo {
    public static void main(String args[]) throws IOException {
        String s = "if (a == 4) a = 0;\n";
        char buf[] = new char[s.length()];
        s.getChars(0, s.length(), buf, 0);
        CharArrayReader in = new CharArrayReader(buf);
        PushbackReader f = new PushbackReader(in);
        int c;

        while ((c = f.read()) != -1) {
            switch (c) {
                case '=':
                    if ((c = f.read()) == '=')
                        System.out.print(".eq.");
                    else {
                        System.out.print("<-");
                        f.unread(c);
                    }
                    break;
                default:
                    System.out.print((char) c);
                    break;
            }
        }
    }
}