score = map(int, raw_input().split())
score.sort()
sum = 0
for i in range(1, 5):
	sum += 100*score[i]
average100 = sum/4
ans = ''
if average100 == 0: ans = '0.00'
else:
	ansstr = str(average100)
	ans = '.'+ansstr[-2]+ansstr[-1]
	for i in range(0, len(ansstr)-2):
		ans = ansstr[-i-3]+ans
	print ans