import java.lang.Math;

public class Program {
    public static void main(String[] args) {

      Vector3[] distances = new Vector3[4];
      distances[0] = new Vector3(16.23, 4.5, 3.2);
      distances[1] = new Vector3(-2, 4, 0);
      distances[2] = new Vector3(-5.2, -3, -0.3);
      distances[3] = new Vector3(15.3, -1.1, 2);

      System.out.print(getTotalDistance(distances));
    }

    static double getTotalDistance(Vector3[] distances)
    {
      double distance = 0;
      for(int x = 0; x < distances.length - 1; x++)
      {
        distance += Vector3.distance(distances[x], distances[x + 1]);
      }
      return distance;
    }
}


public class Vector3 {
  public double X;
  public double Y;
  public double Z;

  public Vector3(double x, double y, double z)
  {
    X = x;
    Y = y;
    Z = z;
  }

  public static double distance(Vector3 a, Vector3 b)
  {
    double deltaX = b.X - a.X;
    double deltaY = b.Y - a.Y;
    double deltaZ = b.Z - a.Z;
    double distance = Math.sqrt(deltaX * deltaX + deltaY * deltaY + deltaZ * deltaZ);
    return distance;
  }
}