$($Please use C$++)$Specifications Read the numerical grades from the grades.txt file and store all the contents in thearray The array should be of int type and have a maximum capacity of $50$ When the user presses v command, display all the contents of the array When the user presses the a command, add a new numerical grade to the file $($useappend mode$)$ When displaying the grades, make sure you display the letter grade instead of thenumerical grade. Use the traditional grading scale for it $($e$.$g$.,$ grade greater orequal to $90$ is an A$,$ grade greater or equal to $80$ is a B$,$ etc.$)$ Make sure the string stream is implemented when reading from the file.