$\"\"$

\

The expression is $\"\"$ .

\

Let $\"\"$ .

\

If $\"\"$ , then .

\

Since $\"\"$ has the same range as $\"\"$ .

\

$\"\"$ .

\

$\"\"$ then $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$ and $\"\"$ .

\

$\"\"$

\

Therefore, $\"\"$ .

\

\

$\"\"$ .