using System;

namespace DistanceTask
{
    public static class DistanceTask
    {
        // Расстояние от точки (x, y) до отрезка AB с координатами A(ax, ay), B(bx, by)
        public static double GetDistanceToSegment(double ax, double ay, double bx, double by, double x, double y)
        {
            double coss;
            double xx, yy;
            xx = bx - ax;
            yy = by - ay;
            double x1, y1;
            x1 = x - ax;
            y1 = y - ay;
            double a, b;
            a = Math.Sqrt(xx * xx + yy * yy);
            b = Math.Sqrt(x1 * x1 + y1 * y1);
            if (by == ay)
            {
                if (x >= bx)
                    return Math.Sqrt(Math.Pow(x - bx, 2) + Math.Pow(y - by, 2));
                else if (x <= ax)
                    return Math.Sqrt(Math.Pow(x - ax, 2) + Math.Pow(y - ay, 2));
                else
                {
                    coss = Math.Abs(x1 * xx + y1 * yy) / (Math.Sqrt(x1 * x1 + y1 * y1) * Math.Sqrt(xx * xx + yy * yy));
                    double sinn;
                    sinn = Math.Sqrt(1 - Math.Pow(coss, 2));
                    double S = a * b * sinn;
                    return S / a;
                }
            }
            else if (ax == bx)
            {
                if ((by >= ay && y >= by) || (by <= ay && y <= by))
                    return Math.Sqrt(Math.Pow(x - bx, 2) + Math.Pow(y - by, 2));
                else if ((ay >= by && y >= ay) || (ay <= by && y <= ay))
                    return Math.Sqrt(Math.Pow(x - ax, 2) + Math.Pow(y - ay, 2));
                else
                {
                    coss = Math.Abs(x1 * xx + y1 * yy) / (Math.Sqrt(x1 * x1 + y1 * y1) * Math.Sqrt(xx * xx + yy * yy));
                    double sinn;
                    sinn = Math.Sqrt(1 - Math.Pow(coss, 2));
                    double S = a * b * sinn;
                    return S / a;
                }
            }
            else
            {
                coss = Math.Abs(x1 * xx + y1 * yy) / (Math.Sqrt(x1 * x1 + y1 * y1) * Math.Sqrt(xx * xx + yy * yy));
                if ((coss <= 0 && bx > ax && x > bx) || (coss <= 0 && ax > bx && x < bx))
                    return Math.Sqrt(Math.Pow(x - bx, 2) + Math.Pow(y - by, 2));
                else if ((coss <= 0 && ax < bx&&x<ax) || (coss <= 0 && ax > bx && x > ax))
                    return Math.Sqrt(Math.Pow(x - ax, 2) + Math.Pow(y - ay, 2));
                else if (Math.Sqrt(x1 * x1 + y1 * y1) * Math.Sqrt(xx * xx + yy * yy) != 0)
                {
                    coss = Math.Abs(x1 * xx + y1 * yy) / (Math.Sqrt(x1 * x1 + y1 * y1) * Math.Sqrt(xx * xx + yy * yy));
                    double sinn;
                    sinn = Math.Sqrt(1 - Math.Pow(coss, 2));
                    double S = a * b * sinn;
                    return S / a;
                }
                else
                    return 0;
            }
        }
    }
}