///Etfsh5t nseet el rank
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
#include "bits/stdc++.h"
using namespace std;

#define pb push_back
#define F first
#define S second
#define f(i, a, b) for (int i = a; i < b; i++)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define sz(x) (int)(x).size()
#define mp(x, y) make_pair(x, y)
#define popCnt(x) (__builtin_popcountll(x))
// #define int ll

using ll = long long;
using ull = unsigned long long;
using uint = uint32_t;
using ii = pair<int, int>;

const int N = 4e5 + 5, A = 12, LG = 18, MOD = (119 << 23) + 1;
const long double PI = acos(-1);
const long double EPS = 1e-9;
const int INF = 1e18;
long double dist[1404][1404];
char grid[777][777];
void doWork()
{
    const long double CURVE_LEN = PI * 2.5;
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            cin >> grid[i][j];
        }
    }

    f(i, 0, n * 2 + 1)
        f(j, 0, m * 2 + 1)
            dist[i][j] = 1e15;

    dist[0][0] = 0.0;
    using pd = pair<long double, ii>;
    priority_queue<pd, vector<pd>, greater<pd> > pq;

    pq.push(make_pair(0.0, ii(0, 0)));

    const int dx[] = {-1, 1, 0, 0};
    const int dy[] = {0, 0, -1, 1};
    while (pq.size())
    {
        auto cur = pq.top();
        pq.pop();
        int x = cur.S.F;
        int y = cur.S.S;
        if (cur.F > dist[x][y])
            continue;
        f(k, 0, 4)
        {
            int nx = x + dx[k];
            int ny = y + dy[k];
            if (nx < 0 || ny < 0 || nx > 2 * n || ny > 2 * m)
                continue;
            if (nx % 2 == 1 && ny % 2 == 1)
                continue;
            if (dist[nx][ny] > dist[x][y] + 5)
            {
                dist[nx][ny] = dist[x][y] + 5;
                pq.push(make_pair(dist[nx][ny], ii(nx, ny)));
            }
        }
        if (y & 1)
        {
            if (x > 0 && grid[x / 2 - 1][y / 2] == 'O' && dist[x - 1][y + 1] > dist[x][y] + CURVE_LEN)
            {
                dist[x - 1][y + 1] = dist[x][y] + CURVE_LEN;
                pq.push(make_pair(dist[x - 1][y + 1], ii(x - 1, y + 1)));
            }
            if (x > 0 && grid[x / 2 - 1][y / 2] == 'O' && dist[x - 1][y - 1] > dist[x][y] + CURVE_LEN)
            {
                dist[x - 1][y - 1] = dist[x][y] + CURVE_LEN;
                pq.push(make_pair(dist[x - 1][y - 1], ii(x - 1, y - 1)));
            }
            if (x < 2 * n && grid[x / 2][y / 2] == 'O' && dist[x + 1][y + 1] > dist[x][y] + CURVE_LEN)
            {
                dist[x + 1][y + 1] = dist[x][y] + CURVE_LEN;
                pq.push(make_pair(dist[x + 1][y + 1], ii(x + 1, y + 1)));
            }
            if (x < 2 * n && grid[x / 2][y / 2] == 'O' && dist[x + 1][y - 1] > dist[x][y] + CURVE_LEN)
            {
                dist[x + 1][y - 1] = dist[x][y] + CURVE_LEN;
                pq.push(make_pair(dist[x + 1][y - 1], ii(x + 1, y - 1)));
            }
        }
        if (x & 1)
        {
            if (y > 0 && grid[x / 2][y / 2 - 1] == 'O' && dist[x + 1][y - 1] > dist[x][y] + CURVE_LEN)
            {
                dist[x + 1][y - 1] = dist[x][y] + CURVE_LEN;
                pq.push(make_pair(dist[x + 1][y - 1], ii(x + 1, y - 1)));
            }
            if (y > 0 && grid[x / 2][y / 2 - 1] == 'O' && dist[x - 1][y - 1] > dist[x][y] + CURVE_LEN)
            {
                dist[x - 1][y - 1] = dist[x][y] + CURVE_LEN;
                pq.push(make_pair(dist[x - 1][y - 1], ii(x - 1, y - 1)));
            }
            if (y < 2 * m && grid[x / 2][y / 2] == 'O' && dist[x + 1][y + 1] > dist[x][y] + CURVE_LEN)
            {
                dist[x + 1][y + 1] = dist[x][y] + CURVE_LEN;
                pq.push(make_pair(dist[x + 1][y + 1], ii(x + 1, y + 1)));
            }
            if (y < 2 * m && grid[x / 2][y / 2] == 'O' && dist[x - 1][y + 1] > dist[x][y] + CURVE_LEN)
            {
                dist[x - 1][y + 1] = dist[x][y] + CURVE_LEN;
                pq.push(make_pair(dist[x - 1][y + 1], ii(x - 1, y + 1)));
            }
        }
    }
    cout << fixed << setprecision(10) << dist[n * 2][m * 2] << '\n';
}
int32_t main()
{
#ifdef ONLINE_JUDGE
    ios_base::sync_with_stdio(0);
    cin.tie(0);
#endif // ONLINE_JUDGE

    int t = 1;
    // cin >> t;
    while (t--)
    {
        doWork();
    }
    return 0;
}