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

const double OO = 1e10, PI = acos(-1), QA = (10.0 / 4.0) * PI;

int main() {
    cin.tie(0);cin.sync_with_stdio(0);
    cout.tie(0);cout.sync_with_stdio(0);
    int h, w; cin >> h >> w;
    vector<string> g(h);
    for (int i = 0; i < h; ++i) {
        cin >> g[i];
    }
    function<int(int, int)> I = [&](int i, int j) {
        return 8 * (i * w + j);
    };
    vector<vector<pair<int, double>>> adj(8 * h * w);
    function<void(int, int)> connect_square = [&](int x, int y) {
        int j = I(x, y);
        for (int k = 0; k < 8; ++k) {
            adj[j + k].emplace_back(j + ((k + 1) % 8), 5.0);
            adj[j + ((k + 1) % 8)].emplace_back(j + k, 5.0);
        }
    };
    function<void(int, int)> connect_circle = [&](int x, int y) {
        connect_square(x, y);
        int j = I(x, y);
        for (int k = 1; k < 8; k += 2) {
            adj[j + k].emplace_back(j + ((k + 2) % 8), QA);
            adj[j + ((k + 2) % 8)].emplace_back(j + k, QA);
        }
    };
    function<void(int, int)> add_zero_edge = [&](int u, int v) {
        adj[u].emplace_back(v, 0.0);
        adj[v].emplace_back(u, 0.0);
    };
    function<void(int, int)> connect_right = [&](int x, int y) {
        if (y + 1 == w) { return; }
        int i = I(x, y), j = I(x, y + 1);
        add_zero_edge(i + 2, j + 0);
        add_zero_edge(i + 3, j + 7);
        add_zero_edge(i + 4, j + 6);
    };
    function<void(int, int)> connect_down = [&](int x, int y) {
        if (x + 1 == h) { return; }
        int i = I(x, y), j = I(x + 1, y);
        add_zero_edge(i + 6, j + 0);
        add_zero_edge(i + 5, j + 1);
        add_zero_edge(i + 4, j + 2);
    };
    for (int i = 0; i < h; ++i) {
        for (int j = 0; j < w; ++j) {
            if (g[i][j] == 'O') {
                connect_circle(i, j);
            } else {
                connect_square(i, j);
            }
            connect_right(i, j);
            connect_down(i, j);
        }
    }
    vector<double> d(8 * h * w, OO);
    set<pair<double, int>> S;
    d[0] = 0.0, S.emplace(0.0, 0);
    while (!S.empty()) {
        int v = S.begin() -> second;
        double dv = S.begin() -> first;
        S.erase(S.begin());
        if (isgreater(d[v], dv) || isless(d[v], dv)) { continue; }
        for (auto [u, w] : adj[v]) {
            if (isgreater(d[u], d[v] + w)) {
                d[u] = d[v] + w, S.emplace(d[u], u);
            }
        }
    }
    cout << fixed << setprecision(6) << d[I(h - 1, w - 1) + 4];
}