bugkExercise 5.5 Calculating average student grades.

//Exercise 5.5 Calculating average student grades.
#include <stdio.h>
#include <stdbool.h>
#include <ctype.h>

int main(void)
{
  size_t nclasses = 0;                  // Number classes
  size_t nstudents_max = 0;             // Maximum number of students in a class
  char answer = ‘N‘;

  printf("How many students are in the largest class? :");
  scanf("%zd", &nstudents_max);
  printf("How many classes are there? :");
  scanf("%zd", &nclasses);
  size_t class = 0;
  size_t student = 0 ;


  int grades[nclasses][nstudents_max];                     // Stores the grades
  size_t students[nclasses];                               // Stores the number of students in each class

  for( class = 0 ; class < nclasses ; ++class)
    {
    printf("Enter the grades for students in class %zd.\n", class + 1);
    students[class] = 0;                                   // Student count within a class
    while(true)
    {
      printf("Enter the integer grade for student %zd: ", students[class] + 1);
      scanf("%d", &grades[class][students[class]]);
      if(++students[class] == nstudents_max)                // Increment and check student count
      {
        printf("Class %zd complete.", class + 1);
        break;
      }
      printf("Any more students in class %zd (Y or N): ", class + 1);
      scanf(" %c", &answer);
      if(toupper(answer) == ‘N‘)
      break;
    }
  }
  printf("\n");
  for( class = 0 ; class < nclasses ; ++class)
    {
    int class_total = 0;
    printf("Student grades for class %zd are:\n", class + 1);
    for( student = 0 ; student < students[class] ; ++student)
    {
      class_total += grades[class][student];
      if((student + 1) % 6 == 0)
        printf("\n");
      printf("%5d", grades[class][student]);
    }
    printf("\nAverage grade for class %zd is %.2lf\n", class + 1, (double)class_total/students[class]);
  }
    return 0;
}