import java.awt.Point;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int H = scan.nextInt();
		int W = scan.nextInt();
		int[][]P = new int[H][W];
		List<Point> list = new ArrayList<Point>();
		for(int i = 0; i < H; i++) {
			String s = scan.next();
			for(int j = 0; j < W; j++) {
				P[i][j] = (int)s.charAt(j) - '0';
				if(P[i][j] == 1) {
					int x = j + 1;
					int y = i + 1;
					Point p = new Point(x, y);
					list.add(p);
				}
			}
		}
		scan.close();

		double l1 = 0;
		double l2 = 0;
		double ans = Double.MAX_VALUE;
		for(int i = 1; i <= W; i++) {
			l1 = 0;
			l2 = 0;
			for(Point p : list) {
				int x = p.x;
				int y = p.y;
				int dx1 = i - x;
				int dy1 = 0 - y;
				l1 += Math.sqrt(dx1 * dx1 + dy1 * dy1);
				int dy2 = H + 1 - y;
				l2 += Math.sqrt(dx1 * dx1 + dy2 * dy2);
			}
			ans = Math.min(ans, l1);
			ans = Math.min(ans, l2);
		}
		for(int i = 1; i <= H; i++) {
			l1 = 0;
			l2 = 0;
			for(Point p : list) {
				int x = p.x;
				int y = p.y;
				int dx1 = 0 - x;
				int dy1 = i - y;
				l1 += Math.sqrt(dx1 * dx1 + dy1 * dy1);
				int dx2 = W + 1 - x;
				l2 += Math.sqrt(dx2 * dx2 + dy1 * dy1);
			}
			ans = Math.min(ans, l1);
			ans = Math.min(ans, l2);
		}
		System.out.println(ans);
	}
}