#write a function yana that doesn't have any parameters
#function reads positive ints, first zero or negative terminates the input
#function returns the average of ints divisible by 5
#if there are no ints divisible by 5 function returns -1
#write main to test your function
def yana():
	total=0
	count=0
	num=int(input("enter int "))
	while(num>0):
		if(num%5==0):
			total+=num
			count+=1
		num=int(input("enter int "))
	if(count>0):
		return total/count
	else:
		return -1

def main():
	res=yana()
	if(res==-1):
		print("no ints div by 5")
	else:

		print("average of div by 5 is", res)
main()