#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
int fx[] = {1, -1, 0, 0};
int fy[] = {0, 0, 1, -1};
int dir[4][2] = {1, 0, -1, 0, 0, -1, 0, 1};
long long gcd(long long a, long long b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
long long p2[1000];
int main() {
  p2[1] = 1;
  for (int i = 2; i <= 40; i++) {
    p2[i] = p2[i - 1] * 2;
  }
  long long n;
  cin >> n;
  for (int i = 1; i <= 40; i++) {
    if (p2[i] > n) {
      cout << i - 1 << endl;
      return 0;
    } else if (p2[i] == n) {
      cout << i << endl;
      return 0;
    }
  }
  return 0;
}
