Write a switch $...$case program, use the following sample programs

use input statement to input $2$ grades, test $1$ and test $2,$ calculate the average.

if the average $=100$ or $>90,$ print "your average grade is: A$".$

$.$ if the average $>80,$ print "your average grade is: B:$".$

if the average $>70,$ print "your average grade is: C:$".$

if the average $>60,$ print "your average grade is: $D".$

else "print F$".$