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).
n = int(input())
A = []
sum = 0
for i in range(n):
    x = int(input())
    sum += x
    A.append(sum/i)

print('%.6f\n' % max(A))