public int ExteriorRingCount {get;}

{
  static void GetExteriorRings(Polygon inputPolygon)
  {
    if (inputPolygon == null || inputPolygon.IsEmpty)
      return;

    // polygon part count
    int partCount = inputPolygon.PartCount;
    // polygon exterior ring count
    int numExtRings = inputPolygon.ExteriorRingCount;
    // get set of exterior rings for the polygon
    IList<Polygon> extRings = inputPolygon.GetExteriorRings();

    // test each part for "exterior ring"
    for (int idx = 0; idx < partCount; idx++)
    {
      bool isExteriorRing = inputPolygon.IsExteriorRing(idx);
      var ring = inputPolygon.GetExteriorRing(idx);
    }
  }
}