#include #include #include #include #include #include using namespace std; namespace { template constexpr T sqrt(T s) { T x = s / 2.0; T prev = 0.0; while (x != prev) { prev = x; x = (x + s / x) / 2.0; } return x; } template struct Sqrt { double ary[N * N]; constexpr Sqrt() : ary() { for (int i = 0; i < N; ++i) for (int j = 0; j < N; ++j) ary[j + i * (N - 1)] = sqrt(static_cast(i * i + j * j)); } }; constexpr int abs(int x) { return x < 0 ? -x : x; } constexpr auto d_map = Sqrt<51>(); constexpr auto distance(int x1, int y1, int x2, int y2) { return d_map.ary[abs(x1 - x2) + abs(y1 - y2) * 50]; } } // namespace int main() { int H, W; cin >> H >> W; // ポイントを作成 vector> pts; for (int y = 1; y <= H; ++y) { string str; cin >> str; for (int x = 1; x <= W; ++x) { if (str.at(x - 1) == '1') pts.push_back({ x, y }); } } double minv = LDBL_MAX; for (int x = 1; x <= W; ++x) { double v1 = 0; double v2 = 0; for (const auto &pt : pts) { v1 += distance(x, 0, pt.at(0), pt.at(1)); v2 += distance(x, H + 1, pt.at(0), pt.at(1)); } minv = min(minv, v1); minv = min(minv, v2); } for (int y = 1; y <= H; ++y) { double v1 = 0; double v2 = 0; for (const auto &pt : pts) { v1 += distance(0, y, pt.at(0), pt.at(1)); v2 += distance(W + 1, y, pt.at(0), pt.at(1)); } minv = min(minv, v1); minv = min(minv, v2); } cout << fixed << setprecision(9) << minv << endl; return 0; }