N = int(input())
for i in range(1, 10 ** 18):
    if 2 ** i > N:
        print(i - 1)
        break

c9bb03af08a3a48218be9531704feb8a3251d581
<mask token>

<mask token>
for i in range(1, 10 ** 18):
    if 2 ** i > N:
        print(i - 1)
        break

N = int(input())
for i in range(1, 10 ** 18):
    if 2 ** i > N:
        print(i - 1)
        break
