#include <stdio.h>
#include <math.h>
int main() {
  int N;
  scanf("%d",&N);
  int n = log(N)/log(2);
  if(N<2) printf("0\n");
  else
    printf("%d\n",log(N)/(n*log(2))==1?n:n+1);
  return 0;
}