import sys
from math import log2
sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


N = I()
P = [I() for _ in range(N)]

F_N = (sum(0.81**i for i in range(1,N+1)))**.5/sum(0.9**i for i in range(1,N+1))
F_inf = 1/19**.5
f_N = 1200*(F_N-F_inf)/(1-F_inf)


def g(x):
    return pow(2,x/800)


def g_inv(y):
    return 800*log2(y)


y = sum(g(P[i-1])*0.9**i for i in range(1,N+1))/sum(0.9**i for i in range(1,N+1))
R = g_inv(y)-f_N
print(int(R+.5))