import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import numpy as np

N = int(readline())
R = np.array(read().split(), np.float64)

x = np.full(N+1,0.9, np.float64); x[0] = 1; np.cumprod(x,out=x)
y = np.full(N+1,0.81, np.float64); y[0] = 1; np.cumprod(y,out=y)
x[0] = 0; y[0] = 0
F = np.sqrt(y.cumsum()) / x.cumsum()

F_inf = ((81/19)**.5)/9

f = (F - F_inf) / (F[1] - F_inf) * 1200

R = np.concatenate([[0],R])
gR = np.exp(R / 800 * np.log(2))
gR *= x

answer = np.log(gR.sum() / x.sum()) / np.log(2) * 800 - f[N]

print(int(answer + .5))