#include <bits/stdc++.h>

using namespace std;

typedef double f64;

const int MAX_N = 700 + 5;
const int MAX_M = 2250000;
const f64 ArcLen = acos(-1) * 2.5;

int N, M;
struct Edge{
    int y, prev;
    f64 len;
}e[MAX_M << 3];
int elast[MAX_M], ecnt;
char str[MAX_N][MAX_N];
int s, t, idxX[MAX_N][MAX_N][2], idxY[MAX_N][MAX_N], tot;
f64 dis[MAX_M];

void Build(int x, int y, f64 z) {
    ecnt ++;
    e[ecnt].y = y;
    e[ecnt].len = z;
    e[ecnt].prev = elast[x];
    elast[x] = ecnt;
}

void add_edge(int x, int y, f64 z) {
    Build(x, y, z); Build(y, x, z);
}

int main() {
    scanf("%d%d", &N, &M);
    for (int i = 0; i <= N; i ++)
        for (int j = 0; j <= M; j ++) {
            idxX[i][j][0] = ++ tot;
            if (j) idxX[i][j][1] = ++ tot;
            if (i) idxY[i][j] = ++ tot;
        }
    s = idxX[0][0][0]; t = idxX[N][M][0];
    for (int i = 0, j = 1; j <= M; j ++) {
        add_edge(idxX[i][j][0], idxX[i][j][1], 5);
        add_edge(idxX[i][j][1], idxX[i][j - 1][0], 5);
    }
    for (int i = 1; i <= N; i ++) {
        scanf("%s", str[i] + 1);
        add_edge(idxX[i][0][0], idxY[i][0], 5);
        add_edge(idxY[i][0], idxX[i - 1][0][0], 5);
        for (int j = 1; j <= M; j ++) {
            add_edge(idxX[i][j][1], idxX[i][j - 1][0], 5);
            add_edge(idxX[i][j][0], idxX[i][j][1], 5);
            add_edge(idxX[i][j][0], idxY[i][j], 5);
            add_edge(idxY[i][j], idxX[i - 1][j][0], 5);
            if (str[i][j] == 'O') {
                add_edge(idxX[i][j][1], idxY[i][j], ArcLen);
                add_edge(idxY[i][j], idxX[i - 1][j][1], ArcLen);
                add_edge(idxX[i - 1][j][1], idxY[i][j - 1], ArcLen);
                add_edge(idxY[i][j - 1], idxX[i][j][1], ArcLen);
            }
        }
    }
    
    for (int i = 1; i <= tot; i ++) dis[i] = 1e100;
    dis[s] = 0;
    priority_queue <pair <double, int>> pq;
    pq.push(make_pair(0, s));
    while (!pq.empty()) {
        int u = pq.top().second;
        f64 d = -pq.top().first;
        pq.pop();
        if (d != dis[u]) continue;
        if (u == t) break;
        for (int i = elast[u]; i; i = e[i].prev) {
            int v = e[i].y;
            if (dis[u] + e[i].len < dis[v]) {
                dis[v] = dis[u] + e[i].len;
                pq.push(make_pair(-dis[v], v));
            }
        }
    }
    printf("%.10lf\n", dis[t]);
    
    return 0;
}