import math
N = int(input())
lsp = [int(input()) for i in range(N)]

def F(k):
    return ((1-0.81**k)/(1-0.81))**(1/2)/((1-0.9**k)/(1-0.9))

def f(k):
    return (F(k)-(1/19**(1/2)))/(F(1)-(1/19**(1/2)))*1200

def g(x):
    return 2**(x/800)

def invg(x):
    return 800*math.log2(x)

v1 = 0
v2 = 0
for c in range(N):
    i = c+1
    v1 += g(lsp[c])*0.9**i
    v2 += 0.9**i

ans = invg(v1/v2)-f(N)
print(int('{:.0f}'.format(ans)))