You want your program to execute statement 1 when A A is false, B B is false, and C C is true, and to execute

You want your program to execute statement 1 when $A$ is false, $B$ is false, and $C$ is true, and to execute statement 2 otherwise. You wrote \section*{if $\mathrm{not}(A$ and $B)$ and $C$ then}

statement 1

else

statement 2

end if

Does this do what you want?