at `a' from start to letter
at char #10: from letter to start
at `1' from start to digit
at char #10: from digit to start
at `a' from start to letter
at `1' from letter to digit
at char #10: from digit to start
at `1' from start to digit
at `a' from digit to letter
at char #10: from letter to start
at EOF: done
