#include <stdio.h>
#include <math.h>
int digi(int a){
	int r, p;
	r = 1;
	p = 1;
	while(a>= p) {
		p = pow(2, r) + p ;
		r = r + 1;
	}
	return r;
}

int main(){
	int x;
	scanf("%d", &x);
	printf("%d\n", digi(x));
	return 0;
}