from math import log,exp,sqrt
def F(n):
    A=B=0
    for i in range(1,n+1):
        A+=0.81**i
        B+=0.9**i

    return sqrt(A)/B

def f(n):
    T=1/sqrt(19)
    return 1200*(F(n)-T)/(1-T)

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

def inverse_g(Y):
    return 800*log(Y,2)
#================================================
N=int(input())
P=[0]*(N+1)
for i in range(1,N+1):
    P[i]=int(input())

A=B=0
for k in range(1,N+1):
    A+=g(P[k])*(0.9**k)
    B+=0.9**k

X=inverse_g(A/B)-f(N)
print(int(X+0.5))