#include <bits/stdc++.h>

#define f first
#define s second
#define pb push_back
#define mp make_pair

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;

const int N = 300500, inf = 1e9, mod = 998244353;
const ll INF = 1e18;

int sum(int a, int b) {
    a += b;
    if (a >= mod)
        a -= mod;
    return a;
}

int sub(int a, int b) {
    a -= b;
    if (a < 0)
        a += mod;
    return a;
}

int mult(int a, int b) {
    return 1ll * a * b % mod;
}

int bp(int a, int b) {
    int res = 1;
    while (b) {
        if (b & 1)
            res = mult(res, a);
        a = mult(a, a);
        b >>= 1;
    }
    return res;
}

int inv(int x) {
    return bp(x, mod - 2);
}
ll s;
typedef double ld;
int h, w;
const int maxN = 2005;
char c[maxN][maxN];
const int maxP = 1405 * 1405;
vector<pair<int,ld>> g[maxP];
int id(int i, int j) {
    return i * (2 * w + 1) + j;
}
ld d[maxP];
void solve() {
    cin >> h >> w;
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            cin >> c[i][j];
        }
    }
    for (int i = 0; i <= 2 * h; i++) {
        for (int j = 0; j <= 2 * w; j++) {
            if (i + 1 <= 2 * h && j % 2 == 0) {
                g[id(i, j)].emplace_back(id(i + 1, j), 5);
                g[id(i + 1, j)].emplace_back(id(i, j), 5);
            }
            if (j + 1 <= 2 * w && i % 2 == 0) {
                g[id(i, j)].emplace_back(id(i, j + 1), 5);
                g[id(i, j + 1)].emplace_back(id(i, j), 5);
            }
        }
    }
    const ld F = 2.5 * acosl(-1.0);
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            if (c[i][j] == 'O') {
                vector<int> PT;
                PT.emplace_back(id(2 * i, 2 * j + 1));
                PT.emplace_back(id(2 * i + 1, 2 * j + 2));
                PT.emplace_back(id(2 * i + 2, 2 * j + 1));
                PT.emplace_back(id(2 * i + 1, 2 * j));
                for (int z = 0; z < PT.size(); z++) {
                    g[PT[z]].emplace_back(PT[(z + 1) % 4], F);
                    g[PT[(z + 1) % 4]].emplace_back(PT[z], F);
                }
            }
        }
    }
    for (int i = 0; i <= 2 * h; i++) {
        for (int j = 0; j <= 2 * w; j++) {
            d[id(i, j)] = 1e18;
        }
    }
    d[0] = 0;
    priority_queue<pair<ld,int>, vector<pair<ld,int>>, greater<>> pq;
    pq.push({d[0], 0});
    while (!pq.empty()) {
        auto it = pq.top();
        pq.pop();
        int v = it.second;
//        cout << v << " ? " << endl;
        if (d[v] != it.first) continue;
        for (auto& it : g[v]) {
            if (d[it.first] > d[v] + it.second) {
                d[it.first] = d[v] + it.second;
                pq.push({d[it.first], it.first});
            }
        }
    }
    cout << fixed << setprecision(12) << d[id(2 * h, 2 * w)] << '\n';
}

int main() {
#ifdef DEBUG
    freopen("input.txt", "r", stdin);
#endif
    ios_base::sync_with_stdio(false);
    int t = 1;
//    cin >> t;
    for (int i = 1; i <= t; i++) {
//        cout << "Case #" << i << endl;
        solve();
    }
}