import times, strutils, sequtils, math, algorithm, tables, sets, lists, intsets
import critbits, future, strformat, deques
template `max=`(x,y) = x = max(x,y)
template `min=`(x,y) = x = min(x,y)
template `mod=`(x,y) = x = x mod y
template scan2 = (scan(), scan())
template scan3 = (scan(), scan())
let read* = iterator: string {.closure.} =
    while true: (for s in stdin.readLine.split: yield s)
proc scan(): int = read().parseInt
proc scanf(): float = read().parseFloat
proc toInt(c:char): int =
    return int(c) - int('0')


const lfinf = sqrt(0.81/0.19)/9.0

proc lf(n:int):float=
  var
    t = 0.0
    d = 0.0
  for i in 1..n:
    t+=pow(0.81,i.float)
    d+=pow(0.9,i.float)
  t = sqrt(t)

  return t/d

proc sf(n:int):float=
  return 1200.float*(lf(n)-lfinf)/(lf(1)-lfinf)

proc g(x:float):float=
  return pow(2.0,x/800)

proc ig(y:float):float=
  return 800.float*log2(y)

proc solve()=
  var
    n = scan()
    rperf = newseqwith(n,scanf())
    t = 0.0
    d = 0.0
  for i in 0..<n:
    t+=g(rperf[i])*pow(0.9,(i+1).float)
    d+=pow(0.9,(i+1).float)
  echo (-sf(n)+ig(t/d)).floor.int

  
solve()