import math

N = int(input())
F = lambda n: math.sqrt(sum([0.81 ** i for i in range(1, n + 1)])) / sum([0.9 ** i for i in range(1, n + 1)])
f = (F(N) - 1 / math.sqrt(19)) / (F(1) - 1 / math.sqrt(19)) * 1200
g = lambda x: 2 ** (x / 800)
g_inv = 800 * math.log(1, 2)
Rating = int(800*math.log((sum([g(int(input())) * (0.9 ** i) for i in range(1, N + 1)]) / sum([0.9 ** i for i in range(1, N + 1)])),2) - f)
print(Rating)