The input contains between 1 and 10 lines, *i*-th line contains an integer number *x*<sub class="lower-index">*i*</sub> (0 ≤ *x*<sub class="lower-index">*i*</sub> ≤ 9).
a = b = c = 0
d = 1
for _ in range(input()):
	x = input()
	a += x
	b += 1
	if a * d < b * c :
		break
	c , d = a , b
print c * 1. / d