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)