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

#define MAXN 4000005

const double QC = 7.85398163397448309615660845820;
const double INF = 1e100;

vector<pair<int, double>> graph[MAXN];
char tmpstr[1000];
int n, m;


// 0 1 2
// 3   4
// 5 6 7
int get_id(int row, int col, int pos)
{
    int x = 1 + row*2;
    int y = 1 + col*2;
    if (pos == 0 || pos == 1 || pos == 2) x--;
    if (pos == 5 || pos == 6 || pos == 7) x++;
    if (pos == 0 || pos == 3 || pos == 5) y--;
    if (pos == 2 || pos == 4 || pos == 7) y++;
    return x*(m*2+1) + y;
}

void add_edge(int x, int y, double w)
{
    graph[x].push_back({y, w});
    graph[y].push_back({x, w});
}



double Dijkstra(int S, int T)
{
    priority_queue<pair<double, int>> Q;
    vector<double> dis(T+10, INF);
    vector<int> vis(T+10);

    dis[S] = 0;
    Q.push({0, S});
    while (!Q.empty()) {
        int u = Q.top().second;
        Q.pop();
        if (vis[u]) continue;
        vis[u] = 1;
        if (u == T) break;
        for (auto [v, w]: graph[u]) {
            if (dis[v] > dis[u] + w) {
                dis[v] = dis[u] + w;
                Q.push({-dis[v], v});
            }
        }
    }
    return dis[T];
}



void solve()
{
    scanf("%d%d", &n, &m);

    for (int i=0; i<m; i++) {
        add_edge(get_id(0, i, 0), get_id(0, i, 1), 5);
        add_edge(get_id(0, i, 1), get_id(0, i, 2), 5);
    }
    for (int i=0; i<n; i++) {
        add_edge(get_id(i, 0, 0), get_id(i, 0, 3), 5);
        add_edge(get_id(i, 0, 3), get_id(i, 0, 5), 5);
    }

    for (int i=0; i<n; i++) {
        scanf("%s", tmpstr);
        for (int j=0; j<m; j++) {
            add_edge(get_id(i, j, 2), get_id(i, j, 4), 5);
            add_edge(get_id(i, j, 4), get_id(i, j, 7), 5);
            add_edge(get_id(i, j, 5), get_id(i, j, 6), 5);
            add_edge(get_id(i, j, 6), get_id(i, j, 7), 5);

            double d = (tmpstr[j] == 'O') ? QC : INF;
            add_edge(get_id(i, j, 1), get_id(i, j, 3), d);
            add_edge(get_id(i, j, 3), get_id(i, j, 6), d);
            add_edge(get_id(i, j, 6), get_id(i, j, 4), d);
            add_edge(get_id(i, j, 4), get_id(i, j, 1), d);
        }
    }

    int start = 0;
    int end = get_id(n-1, m-1, 7);
    printf("%.13lf\n", Dijkstra(start, end));
}




int main()
{
    solve();
}