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=[0,0]
mx=0
for i in range(int(input())):
    s=int(input())
    a[s]+=1
    mx=max(mx,a[1]/(a[1]+a[0]))
print(mx)
            
