#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using Graph=vector<vector<int>>;
#define MOD 1000000007

/*
srand((unsigned int)time(NULL));
for(int i=0;i<10;i++){
  cout<<rand()%6+1<<" ";
}
*/
/*
clock_t start,end;
start=clock();
end=clock();
double t=(double)(end-start)/CLOCKS_PER_SEC;
t<2.9;
*/

int main(){
  int N;
  cin>>N;
  int ans=0;
  while(N>1){
    ans++;
    N=(N-1)/2+1;
  }
  cout<<ans<<endl;
}