n = int(input())
H = list(map(int, input().split()))
H.sort()
ans = 0
if n > 63:
    ans += n - 63
    H = H[:63]
    n = 63


now = 0
while 1:
    M = H[:]
    for i in range(now-1, -1, -1):
        M.sort(reverse = True)
        t = 1 << i
        M[0] -= t
        if M[0] <= 0:
            M = M[1:]
        if not M:
            print(now + ans)
            exit()
        M.sort(reverse = True)
    now += 1