Daily Programming Dose day 3

You have a circle of radius r and center in point (x, y). You want the circle center to be in new position (x‘, y‘).

In one step you can put a pin to the border of the circle in a certain point, then rotate the circle around that pin by any angle and finally remove the pin.

What are the minimum number of steps in which the goal could be achieved?

Input

Input consists of 5 space-separated integers r, x, y, x y (1 ≤ r ≤ 105,  - 105 ≤ x, y, x‘, y‘ ≤ 105), circle radius, coordinates of original center of the circle and coordinates of destination center of the circle respectively.

Output

Output a single integer — minimum number of steps required to move the center of the circle to the destination point.

Sample test(s)
input
2 0 0 0 4
output
1
input
1 1 1 4 4
output
3
input
4 5 6 5 6
output
0
Note

In the first sample test the optimal way is to put a pin at point (0, 2) and rotate the circle by 180 degrees counter-clockwise (or clockwise, no matter).

2531a11297bd51456534008e7aef3800a936f20d

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