#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18;
const long long mod = 1e9 + 7;
int main() {
  ios_base::sync_with_stdio(false);
  long long p = 1, n, ans = 1;
  cin >> n;
  while (p <= n) {
    ++ans;
    p *= 2;
  }
  cout << ans - 1;
  return 0;
}
