/* 
Write a function double random_ave(int size) 
that has one integer parameter, size.  
The function reads size  integers. 
The function returns the average of even numbers between 11 and 33. 
If there are no such numbers, the function returns -1. 
Write main that test the function
*/

#include<stdio.h>
double random_ave(int);

int main(){
	int size;
	double res;
	printf("enter size\n");
	scanf("%d",&size);	
	if(size>0){
		res=random_ave(size);
		if(res==-1)
			printf("no evens between 11 and 33\n");
		else
			printf("ave=%f\n",res);
	}
	else
		printf("invalid input\n");

	return 0;
	
}

double random_ave(int size){
	int i, num, sum=0, count=0;
	printf("enter %d integers\n",size);
	for(i=0;i<size;i++){
		scanf("%d",&num);
		if(num%2==0 && num>=11 && num<=33){
			sum+=num;
			count++;
		}
	}
	if(count>0)
		return (double)(sum)/count;
	else
		return -1.0;
}