There is a circle of radius R with center (x,y) and the line which is given by the coordinates of its two points. What is the length of the line segment lies inside the circle?
   Input

The string with 7 numbers is given: the radius of the circle, the coordinates x, y of the center and 2points of the line. All numbers are integers, their absolute value does not exceed 10000. 2points don’t coincide.

   Output

  Print the desired length with 5 digits after the decimal point. If the circle and the line do not intersect, print -1, if touches - print 0.

Samples