1.
Let A={1,2,3,…,10}A = \{1, 2, 3, \ldots, 10\} and f:A→Af: A \to A be defined as
f(k)={k+1,if k is oddk,if k is evenf(k) = \begin{cases} k+1, & \text{if } k \text{ is odd}\\ k, & \text{if } k \text{ is even} \end{cases}
Then the number of possible functions g:A→Ag: A \to A such that g∘f=fg\circ f = f is: