public static boolean search(String a, String b, String c) {
    int len = c.length();
    boolean found1 = false;
    boolean found2 = false;

    for (int i = 2; i <= a.length() - len; i++)
        if (a.substring(i, i + len).equals(c))
            if (a.substring(i - 2, i).equals("aa"))
                found1 = true;

    for (int i = 2; i <= b.length() - len; i++)
        if (b.substring(i, i + len).equals(c))
            if (b.substring(i - 2, i).equals("aa"))
                found2 = true;

    return found1 && found2;
}