Main.java:18: error: incompatible types: unexpected return value
        	return ans.add(cur.toString());
        	              ^
Main.java:23: error: cannot find symbol
        cur.delete(cur.length-1);
                      ^
  symbol:   variable length
  location: variable cur of type StringBuilder
Main.java:28: error: cannot find symbol
        cur.delete(cur.length-1);
                      ^
  symbol:   variable length
  location: variable cur of type StringBuilder
3 errors