/* write a program that first reads number of student in the class
and finds the average B grade (B grade: 80 - 89)

*/
#include<stdio.h>
int main(){
	int num_students, grade,i=0, sum_B=0, count_B=0;
	double ave_grade;


	printf("enter number of students\n");
	scanf("%d",&num_students);
	if(num_students>0){
		printf("entre %d grades\n", num_students);
		while(i<num_students){
			scanf("%d",&grade);
			if(grade>=80 && grade<=89){
				sum_B+=grade;
				count_B++;
			}
			i++;
		}
		if(count_B>0){
			ave_grade=(double)(sum_B)/count_B;
			printf("there are %d students got B grade\n",count_B);
			printf("B grade average is %.1f\n",ave_grade);
		}
		else
			printf("no B grades\n");


	}
	else
		printf("no students in this class\n");

	return 0;
}