import sys
sys.setrecursionlimit(10**7)
def g(n,p):
  if p==N:
    cnt=0
    while n%2==0:
      cnt+=1
      n//=2
    return cnt
  num=p
  c=b.copy()
  for i in str(n):
    c[int(i)-1]-=1
  for k in range(9):
    if c[k]>0 and (n+(k+1)*pow(10,p))%pow(2,p+1)==0:
      num=max(num,g(n+(k+1)*10**p,p+1))
  return num

N=int(input())
b=list(map(int,input().split()))
print(g(0,0))