#include <iostream>
#include <algorithm>

int main() {

  long i, j, k;
  long ans;
  long count = 0;
  std::string str;

  long N;

  std::cin >> N;

  N--;

  while(N != 0) {
    count += 1;
    N >>= 1;
  }

  std::cout << count << std::endl;
  
  return 0;
}