using namespace std;
#include <bits/stdc++.h>
#define BEGIN ios_base::sync_with_stdio(0);cin.tie(0);
#define END return EXIT_SUCCESS;
#define FOR(I,A,B) for(int (I)=(A);(I)<(B);++(I))
int main()
{
	BEGIN
	int N;cin>>N;
	int a=1;
	for(int i=1;;i<<=1,++a)
	{
		if(N<=i)break;
	}
	cout<<(a-1)<<endl;
	END
}