from collections import defaultdict,Counter,deque
from heapq import heappush,heappop,heapify
from bisect import bisect,bisect_left
from itertools import product,permutations,combinations,combinations_with_replacement
from math import gcd
import sys
from functools import lru_cache
if len(sys.argv)==2:sys.stdin=open(sys.argv[1])
input=sys.stdin.readline
sys.setrecursionlimit(10**9)

N=int(input())
print((N-1).bit_length())