public class test {
    static int variable;

    static String concat() {
        String m = "";

        m += "a";
        m += makeString();
        m += "b";
        m += "c";
        return m;
    }

    static String append() {
        StringBuffer b = new StringBuffer();
        b.append("a");
        b.append(makeString());
        b.append("b");
        b.append("c");
        return b.toString();
    }

    static String makeString() {
        return "some" + variable++;
    }
}