from heapq import *

N=int(input())
H=list(map(int,input().split()))
H=[-x for x in H]
heapify(H)
ok=N+100
ng=0
while ok-ng>1:
    mid=(ok+ng)//2
    hp=H[:]
    for i in reversed(range(mid)):
        if i>60:
            heappop(hp)
        else:
            h=heappop(hp)
            if h+(1<<i)<0:
                heappush(hp,h+(1<<i))
        if not hp:
            break
    if hp:
        ng=mid
    else:
        ok=mid
print(ok)