#include <bits/stdc++.h>
using namespace std;

double find_min_d(const vector<string> & P, const int H, const int W, int X, int Y, double tmp = 1e9){
    double d = 0;
    for (int y = 0; y < H; ++y){
        for (int x = 0; x < W; ++x){
            if (P[y][x] == '1'){
                d += sqrt((x - X)*(x - X) + (y - Y) * (y - Y));
            }
        }
        if (d > tmp) break;
    }
    return min(tmp, d);
}

int main() {
    int H, W;
    cin >> H >> W;
    vector<string> P(H);
    for (auto & p : P) cin >> p;
    double ans = 1e9;
    for (int Y = 0; Y < H; ++Y) ans = find_min_d(P, H, W, -1, Y, ans);
    for (int Y = 0; Y < H; ++Y) ans = find_min_d(P, H, W, W, Y, ans);
    for (int X = 0; X < W; ++X) ans = find_min_d(P, H, W, X, -1, ans);
    for (int X = 0; X < W; ++X) ans = find_min_d(P, H, W, X, H, ans);
    cout << fixed << setprecision(15) << ans << endl;
    return 0;
}