/* 
Write a function double random_ave(int size) 
that has one integer parameter, size.  
The function generates size  integers between 0 and 50. 
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 on random size
*/

#include<stdio.h>
#include<stdlib.h>
#include<time.h>

double random_ave(int);

int main(){
	srand(time(NULL));
	int size = rand()%11;
	printf("size is %d\n",size);
	double res;

	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;
	for(i=0;i<size;i++){
		num=rand()%51;
		printf("%d ",num);
		if(num%2==0 && num>=11 && num<=33){
			sum+=num;
			count++;
		}
	}
	printf("\n");
	if(count>0)
		return (double)(sum)/count;
	else
		return -1.0;
}