Write a program to do the following. In main function, the program should define an integer array and a pointer that points to the array. it
will ask the user to input 25 students' scores (scores are between 0 and 100 inclusive, so need to do
input validation), then pass the pointer and its size to a function. The function should find the
corresponding letter grades and return the pointer that points to the array of letter grades.
Also pass the score pointer and its size to the other function, which will calculate the average of those
25 scores with the lowest and highest score dropped, and then return the average (double type).
The input of those scores and output of the letter scores and average must be in main function, and
there is no input and output in the functions besides main function.
No global variables are allowed.
90-100 (include 90 and 100) is A
80-90 (include 80 but not include 90) is B
70-80 (include 70 but not include 80) is C
60-70 (include 60 but not include 70) is D
below 60 is F