#!/usr/bin/env ruby
# frozen_string_literal: true

require_relative "graph"

class Main
  def run
    input = $stdin.readlines(chomp: true)
    graph = Graph.new(input)

    total = dfs(graph.start, graph, 0, Set.new)
    puts total
  end

  def dfs(next_point, graph, total, visited)
    if next_point.y > graph.height || visited.include?(next_point)
      return total
    end

    if graph.at(next_point) == "^"
      step_west = Point.new(next_point.x - 1, next_point.y)
      step_east = Point.new(next_point.x + 1, next_point.y)

      if graph.at(step_west) == "." ||
          graph.at(step_east) == "."
        total += 1
      end

      # step west then dfs south
      total = dfs(step_west, graph, total, visited)
      # step east then dfs south
      total = dfs(step_east, graph, total, visited)
      return total
    elsif graph.at(next_point) == "."
      visited.add(next_point)
    end

    dfs(Point.new(next_point.x, next_point.y + 1), graph, total, visited) # south
  end
end

Main.new.run