#include <iostream>
#include <queue>
#include <vector>
using namespace std;
const int maxn = 105;
const int INF = 2e8;
char mat[maxn][maxn];
const int di[4] = {-1, 1, 0, 0};
const int dj[4] = {0, 0, -1, 1};

int n, m;

int bfs(pair<int, int> p1, pair<int, int> p2) {
    int si = p1.first, sj = p1.second;
    int ei = p2.first, ej = p2.second;
    queue<int> q;
    q.push(si);
    q.push(sj);
    q.push(0);

    vector<vector<bool>> visited(n, vector<bool>(m, false));
    visited[si][sj] = true;

    while(!q.empty()) {
        int ci = q.front(); q.pop();
        int cj = q.front(); q.pop();
        int dist = q.front(); q.pop();

        if(ci == ei and cj == ej) {
            return dist;
        }

        for(int k = 0; k < 4; k++) {
            int ti = ci + di[k];
            int tj = cj + dj[k];

            if(ti >= 0 and ti < n and tj >= 0 and tj < m and !visited[ti][tj] and mat[ti][tj] != '#') {
                visited[ti][tj] = true;
                q.push(ti);
                q.push(tj);
                q.push(dist + 1);
            }
        }
    }

    return INF;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> m;

    int si = 0, sj = 0, ei = 0, ej = 0;
    vector<pair<int, int>> v;
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < m; j++) {
            cin >> mat[i][j];

            if(mat[i][j] == 'D') {
                v.push_back({i, j});
            }

            if(mat[i][j] == 'S') {
                si = i;
                sj = j;
            }
            if(mat[i][j] == 'B') {
                ei = i;
                ej = j;
            }
        }
    }

    int res = INF;
    pair<int, int> S = {si, sj};
    pair<int, int> E = {ei, ej};
    if((int) v.size() == 1) {
        res = bfs(S, v[0]) + bfs(v[0], E);
    }
    else if((int) v.size() == 2) {
        res = bfs(S, v[0]) + bfs(v[0], v[1]) + bfs(v[1], E);
        res = min(res, bfs(S, v[1]) + bfs(v[1], v[0]) + bfs(v[0], E));
    }
    else {
        res = bfs(S, v[0]) + bfs(v[0], v[1]) + bfs(v[1], v[2]) + bfs(v[2], E);
        res = min(res, bfs(S, v[0]) + bfs(v[0], v[2]) + bfs(v[2], v[1]) + bfs(v[1], E));
        res = min(res, bfs(S, v[1]) + bfs(v[1], v[0]) + bfs(v[0], v[2]) + bfs(v[2], E));
        res = min(res, bfs(S, v[1]) + bfs(v[1], v[2]) + bfs(v[2], v[0]) + bfs(v[0], E));
        res = min(res, bfs(S, v[2]) + bfs(v[2], v[0]) + bfs(v[0], v[1]) + bfs(v[1], E));
        res = min(res, bfs(S, v[2]) + bfs(v[2], v[1]) + bfs(v[1], v[0]) + bfs(v[0], E));
    }
    if(res >= INF) res = -1;
    cout << res << endl;
    return 0;
}