H, W = gets.split.map &:to_i
$board = $<.map{|s|s.to_i(2)}

def f(a, b)
  (a**2 + b**2) ** 0.5
end

def g(yy, xx)
  sum = 0
  H.times{|y|
    W.times{|x|
      next if $board[y][x] != 1
      sum += f(xx - x, yy - y)
    }
  }
  sum
end

ans = 1.0/0
(0...H).each{|yy|
  [-1, W].each{|xx|
    ans = [ans, g(yy, xx)].min
  }
}
(0...W).each{|xx|
  [-1, H].each{|yy|
    ans = [ans, g(yy, xx)].min
  }
}
p ans