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

#define all(x) begin(x), end(x)
#ifdef CKISEKI
#define safe cerr << __PRETTY_FUNCTION__ << " line " << __LINE__ << " safe\n"
#define debug(a...) debug_(#a, a)
#define orange(a...) orange_(#a, a)
#include <experimental/iterator>
void debug_(auto s, auto ...a) {
  cerr << "\e[1;32m(" << s << ") = (";
  int f = 0;
  (..., (cerr << (f++ ? ", " : "") << a));
  cerr << ")\e[0m\n";
}
void orange_(auto s, auto L, auto R) {
  cerr << "\e[1;33m[ " << s << " ] = [ ";
  using namespace experimental;
  copy(L, R, make_ostream_joiner(cerr, ", "));
  cerr << " ]\e[0m\n";
}
#else
#define safe ((void)0)
#define debug(...) safe
#define orange(...) safe
#endif

using llf = long double;

const llf PI = acos(llf(-1));

template <typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, m;
  cin >> n >> m;
  vector<string> a(n);
  for (auto &ai : a)
    cin >> ai;

  auto Enc = [&](int x, int y) {
    return x * (2 * m + 1) + y;
  };

  vector<vector<pair<int, llf>>> g((2 * n + 1) * (2 * m + 1));
  auto add_edge = [&g](int x, int y, llf d) {
    g[x].emplace_back(y, d);
    g[y].emplace_back(x, d);
  };
  for (int i = 0; i < 2 * n; ++i)
    for (int j = 0; j < 2 * m + 1; j += 2)
      add_edge(Enc(i, j), Enc(i + 1, j), 5);
  for (int i = 0; i < 2 * n + 1; i += 2) 
    for (int j = 0; j < 2 * m; ++j)
      add_edge(Enc(i, j), Enc(i, j + 1), 5);
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      if (a[i][j] != 'O')
        continue;
      add_edge(Enc(i * 2, j * 2 + 1), Enc(i * 2 + 1, j * 2 + 2), 5 * PI / 2);
      add_edge(Enc(i * 2 + 1, j * 2 + 2), Enc(i * 2 + 2, j * 2 + 1), 5 * PI / 2);
      add_edge(Enc(i * 2 + 2, j * 2 + 1), Enc(i * 2 + 1, j * 2), 5 * PI / 2);
      add_edge(Enc(i * 2 + 1, j * 2), Enc(i * 2, j * 2 + 1), 5 * PI / 2);
    }
  }

  vector<llf> d(g.size(), numeric_limits<llf>::max());
  min_heap<pair<llf, int>> pq;
  pq.emplace(d[0] = 0, 0);
  while (not pq.empty()) {
    auto [l, u] = pq.top();
    pq.pop();
    if (d[u] != l)
      continue;
    for (auto [v, w] : g[u]) {
      if (d[v] > d[u] + w) {
        pq.emplace(d[v] = d[u] + w, v);
      }
    }
  }
  cout << fixed << setprecision(20) << d.back() << '\n';
  return 0;
}