import heapq
N = int(input())
H = sorted(list(map(int,input().split())),reverse=True)
hmax = H[0]
kmax = 0
while 1<<kmax<=hmax:
    kmax += 1
low = N-1
high = N+kmax
while high-low>1:
    mid = (high+low)//2
    heap = [-H[i] for i in range(N)]
    for i in range(mid-1,-1,-1):
        if len(heap)==0:break
        h = -heapq.heappop(heap)
        h -= 1<<i
        if h>0:
            heapq.heappush(heap,-h)
    if len(heap)==0:
        high = mid
    else:
        low = mid
print(high)