#include <stdio.h>

struct student
{
   int     id;
   char    name [ 32 ];
   double  grade [ 4 ];
};

void show(struct student *student)
{
   static const char letter[] = "FDCBA";
   size_t i;
   double sum = 0;
   for ( i = 0; i < sizeof student->grade / sizeof *student->grade; ++i )
   {
      sum += student->grade[i];
   }
   sum /= i;
   printf("%3d %-31s %c\n", student->id, student->name, letter [ (int)sum ] );
}

int main(void)
{
   struct student coder[] =
   {
      { 123, "Slim Pickens",  {1,2,3,4} },
      { 125, "Guy Wire",      {2,2,3,2} },
      { 128, "MaeFlowers",    {0,1,1,1} },
      { 132, "June Meadows",  {2,1,1,2} },
      { 121, "April Showers", {3,3,3,3} },
      { 119, "Les Ismoore",   {1,2,3,4} },
      { 137, "Harry Legg",    {3,2,3,3} },
      { 142, "Sara Bellum",   {4,2,3,4} },
      { 159, "Pete Moss",     {4,4,4,4} },
   };
   size_t i;
   for ( i = 0; i < sizeof coder / sizeof *coder; ++i )
   {
      show(&coder[i]);
   }
   return 0;
}

/* my output
123 Slim Pickens                    C
125 Guy Wire                        C
128 MaeFlowers                      F
132 June Meadows                    D
121 April Showers                   B
119 Les Ismoore                     C
137 Harry Legg                      C
142 Sara Bellum                     B
159 Pete Moss                       A
*/