#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n;
  cin >> n;
  long long l = 1, r = 32;
  long long ans;
  while (l <= r) {
    long long mid = (l + r) / 2;
    if (pow(2, mid) - 1 >= n) {
      ans = mid;
      r = mid - 1;
    } else
      l = mid + 1;
  }
  cout << ans << endl;
  return 0;
}
