Kozak Vus and the Magical Boots

Friends of Cossack Vus have received a secret letter containing an ancient blueprint for magical boots. These boots enable the wearer to accelerate to incredible speeds, starting at an initial speed of $1$ meter per second.

When wearing these magical boots, if a person's current speed is $a$ meters per second, they can cast one of two spells:

• Increase their speed by $a$ meters per second.

• Increase their speed by $a+1$ meters per second.

Determine the minimum number of spells needed for a person in these magical boots to reach exactly $k$ meters per second.

Giriş verilənləri

The input consists of a single integer $k$ ($1\le k\le 10^{18}$) — the target speed to be achieved.

It is guaranteed that reaching the specified speed is possible in a finite number of steps.

Çıxış verilənləri

Output a single integer — the minimum number of spells required to reach the target speed.

Nümunələr

Qeyd

In the first example, the initial speed is already $1$, so no spells are needed.

In the second example, you can use the first type of spell to increase the speed by $1$ meter per second, reaching $2$ meters per second.

In the third example, you can apply the first spell, then the second spell, and finally the first spell again. The speed progression will be: $1\to 2\to 5\to 10$. It can be demonstrated that fewer spells are insufficient to achieve this speed.