B. Amr and Pins (Codeforces Round #287 (div2))

Amr loves Geometry. One day he came up with a very interesting problem. Amr has a circle of radius r and center in point ( x ,? y ) . He wants the circle center to be in new position ( x ',? y ') . In one step Amr can put a pin to the bord

Amr loves Geometry. One day he came up with a very interesting problem.

Amr has a circle of radius r and center in point (x,?y). He wants the circle center to be in new position (x',?y').

In one step Amr 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.

Help Amr to achieve his goal in minimum number of steps.