#!/usr/bin/ruby
# Find all whitespaces reachable from upper left corner and mark them
# with decimal digits.

# Load input
maze = []
ARGF.each_line{|line| maze.push(line)}
height = maze.size
if height <= 0
   puts "Emtpy input"
   exit 1
end
if maze[0][0] != ' '
   puts "Upper left corner is not whitespace"
   exit 1
end

# Breadth-first expansion.
visited = {}
visit_queue = [[0, 0, 0]]
while visit_queue.size > 0
   y, x, d = visit_queue.shift
   if y < 0 || y >= height || x < 0 || maze[y][x] != ' '
      next
   end
   key = [y, x]
   if visited[key]
      next
   end

   # Mark current cell as reachable and record distance to reach it
   visited[key] = d

   # Expand neighbors
   [[-1, 0], [1, 0], [0, -1], [0, 1]].each{|dy, dx|
      visit_queue.push([y + dy, x + dx, d + 1])
   }
end

# Mark distances
visited.each{|p, d|
   maze[p[0]][p[1]] = ((d % 10) + '0'.ord).chr
}

maze.each{|line| puts line}