#include <stdio.h>

/* Prototypes */
char letter_grade(float score); 

/***************************************/
/* The program reads two values and    */
/* generates the average. You need to  */
/* provide two values separated by and */
/***************************************/
int main() {
   float score1 = 77, score2 = 88, avg;
   int values_read;

   /* Reading the values */
   printf("Enter two scores using <score1> and <score2> format: ");
   values_read = scanf("%f and %f", &score1, &score2);
   printf("The number of values read is %d\n", values_read);

   /* Computing and printing the average */
   avg = (score1 + score2) / 2;
   printf("Average for %f and %f is %.2f\n", score1, score2, avg);
   printf("Your letter grade is %c\n", letter_grade(avg));

   return 0;
}

/******************************************/
/* letter_grade returns 'A; if score >=90 */
/* 'B' if score >=80, 'F' otherwise       */
/******************************************/
char letter_grade(float score) {
   if (score >= 90) {
      return 'A';
   } else if (score >= 80) {
      return 'B';
   } else {
      return 'F';
   }
}