i don't understand why. maybe somebody could help...
here's the code

from math import sqrt
n=int(input())
l=0
a=[None]*n
b=[None]*n
for k in range(n):
    a[k]=int(input())
for z in range(n):
    p=0
    for i in range(n):
        if a[i]>p:
            p=a[i]
            l=i
    b[z]=n-1-l
    a[l]=-a[l]
for z in range(n):
    a[z]=-a[z]
while n>1:
     n=n-1
     a[b.index(n-1)]=2*sqrt(a[b.index(n)]*a[b.index(n-1)])
print('{:.2f}'.format(a[b[0]]))

Edited by author 27.10.2020 23:40