import java.io.InputStream;
import java.io.PrintWriter;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.PriorityQueue;
import java.util.Scanner;
import java.util.Set;
import java.util.Stack;
import java.util.TreeMap;
import java.util.TreeSet;

import static java.util.Comparator.*;

public class Main {
    public static void main(String[] args) {
        PrintWriter out = new PrintWriter(System.out);
        Solver solver = new Solver(System.in, out);
        solver.solve();
        out.close();
    }
}
class Solver {
	Scanner sc;
	PrintWriter out;
    public Solver(InputStream in, PrintWriter out) {
    	sc = new Scanner(in);
    	this.out = out;
    }
    // ==================================================================
    public void solve() {
    	int H = Integer.parseInt(sc.next());
    	int W = Integer.parseInt(sc.next());
    	char[][] C = new char[H][];
    	for (int i = 0; i < H; i++) {
			C[i] = sc.next().toCharArray();
		}
    	double ans = 999999999, wk;
    	for (int i = 0; i <= H + 1; i += (H+1)) {
			for (int j = 1; j <= W; j++) {
				wk = 0;
				for (int y = 0; y < H; y++) {
					for (int x = 0; x < W; x++) {
						if(C[y][x] == '1') {
							wk += Math.sqrt((x+1 - j)*(x+1 - j) + (y+1 - i)*(y+1 - i));
						}
					}
				}
				ans = Math.min(ans, wk);
			}
		}
    	for (int i = 1; i <= H; i++) {
			for (int j = 0; j <= W + 1; j += (W+1)) {
				wk = 0;
				for (int y = 0; y < H; y++) {
					for (int x = 0; x < W; x++) {
						if(C[y][x] == '1') {
							wk += Math.sqrt((x+1 - j)*(x+1 - j) + (y+1 - i)*(y+1 - i));
						}
					}
				}
				ans = Math.min(ans, wk);
			}
		}
    	out.println(ans);
    }
}