#N,X,Q=map(int, input().split())

N=int(input())
H=list(map(int, input().split()))
H=sorted(H)

ng,ok=0,100+N+1
import heapq
while ok-ng>1:
  mid=(ok+ng)//2 
  C=[1]
  for i in range(mid-1):
    C.append(C[-1]*2)
    if C[-1]>10**18:
      C[-1]=10**18
      
  E=[]
  for h in H:
    heapq.heappush(E,-h)
  for c in C[::-1]:
    d=heapq.heappop(E)
    d*=-1 
    e=d-c 
    if e>0:
      heapq.heappush(E,-e)
    if len(E)==0:
      break
      
  if len(E)==0:
    ok=mid 
  else:
    ng=mid
print(ok)