public static long Part1()
{
var root = AreaTraversal <Day15Cell> .Bfs(area, (0, 0), c => c == Day15Cell.Open);
var oxygenNode = AreaTraversal <Day15Cell> .FindPosition(MazeGenerator.OxygenSystemPosition, root);
return(AreaTraversal <Day15Cell> .DepthOf(oxygenNode));
}