#include<stdio.h>
int main()
{
	int n;
	scanf("%d", &n);
	int ans = 0;
	int r = 1;
	while (r * 2 < n)
	{
		ans++;
		r *= 2;
	}
	if (n == 1)
		ans = -1;
	printf("%d\n", ans + 1);
}