Problem Statement

Takahashi is standing at the origin of a two-dimensional plane.
By taking one step, he can move to a point whose Euclidian distance from his current position is exactly R (the coordinates of the destination of a move do not have to be integers). There is no other way to move.
Find the minimum number of steps Takahashi has to take before reaching (X, Y).
We remind you that the Euclidian distance between points (x_1,y_1) and (x_2,y_2) is $\sqrt{(x_1-x_2)^2+(y_1-y_2)^2}$.

Input

Input is given from Standard Input in the following format:
R X Y

Output

Print the minimum number of steps Takahashi has to take before reaching (X, Y).

Constraints

• $1 \leq R \leq 10^5$
• $0 \leq X,Y \leq 10^5$
• $(X,Y) \neq (0,0)$
• All values in input are integers.

Sample Input 1

5 15 0

Sample Output 1

3

He can reach there in three steps: $(0,0) \to$ $(5,0) \to$ $(10,0) \to$ (15,0).
This is the minimum number needed: he cannot reach there in two or fewer steps.

Sample Input 2

5 11 0

Sample Output 2

3

One optimal route is $(0,0) \to$ $(5,0) \to$ $(8,4) \to$ (11,0).

Sample Input 3

3 4 4

Sample Output 3

2

One optimal route is $(0,0) \to$ $(2-\frac{\sqrt{2}}{2}, 2+\frac{\sqrt{2}}{2}) \to$ (4,4).

见题面 Input 部分

见题面 Output 部分