func main()
	var ss: [][]char :: cui@input().split(" ")
	var h: int :: ss[0].toInt(&)
	var w: int :: ss[1].toInt(&)
	var p: [][]char :: #[h, w]char
	for i(0, h - 1)
		do p[i] :: cui@input()
	end for
	var ans: float :: 100000000.0
	var num: int :: 2 * h + 2 * w
	var posX: []int :: #[0]int
	var posY: []int :: #[0]int
	for x(0, w - 1)
		do posX :~ [x, x]
		do posY :~ [-1, h]
	end for
	for y(0, h - 1)
		do posX :~ [-1, w]
		do posY :~ [y, y]
	end for
	for i(0, num - 1)
		var mx: float :: posX[i] $ float
		var my: float :: posY[i] $ float
		var t: float :: 0.0
		for y(0, h - 1)
			for x(0, w - 1)
				if(p[y][x] = '1')
					do t :+ lib@dist(mx, my, x $ float, y $ float)
				end if
			end for
		end for
		do ans :: [ans, t].min()
	end for
	do cui@print("\{ans.toStrFmt(".8f")}\n")
end func