N=int(input())
H=list(map(int,input().split()))
H.sort()
ng=0
ok=N+100
while ok-ng>1:
    mid=(ok+ng)//2
    now=mid
    h=H[:]
    while h and now>61:
        now-=1
        h.pop()
    if not h:
        ok=mid
        continue
    if len(h)>now:
    	ng=mid
    	continue
    for i in range(now-1,-1,-1):
        mx=(-1,-1)
        for j in range(len(h)):
            mx=max(mx,(h[j],j))
        h[mx[1]]-=1<<i
    if max(h)<=0:
        ok=mid
    else:
        ng=mid
print(ok)