#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

// g <- pair < v , cost > 
template < class T >
vector< T > bfs(vector<vector<pair<int, T>>> &graph, int s) {
    T INF = numeric_limits< T >::max();
    vector<T> dist(graph.size(), INF);
    queue<pair<T,int>> q;
    q.push({dist[s] = T(0), s});
    while(!q.empty()){
        auto [uc, ui] = q.front(); q.pop();
        if(uc != dist[ui]) continue;
        for(auto [vi, vc] : graph[ui]) if(dist[vi] > uc + vc) 
            q.push({dist[vi] = uc + vc, vi});
    }
    return dist;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int W,H; cin >> W >> H;
    vector<string> C(H);
    rep(i,H) cin >> C[i];

    vector<pair<int,int>> S, T;
    int di[] = {0, 1, 0, -1};
    int dj[] = {1, 0, -1, 0};
    auto f = [&](vector<pair<int,int>> &V, char X) {
        rep(i,H)rep(j,W) if(C[i][j] == '.') {
            queue<pair<int,int>> q;
            q.push({i, j});
            V.push_back({i, j});
            C[i][j] = X;
            while(!q.empty()) {
                auto [ci, cj] = q.front(); q.pop();
                rep(d,4) {
                    int ni = ci + di[d], nj = cj + dj[d];
                    if(0 <= ni && ni < H && 0 <= nj && nj < W && C[ni][nj] == '.') {
                        C[ni][nj] = X;
                        V.push_back({ni, nj});
                        q.push({ni, nj});
                    }
                }
            }
            return;
        }
    };

    f(S, 'S');
    f(T, 'T');
    vector<vector<pair<int,int>>> G(H * W + 2);
    auto h = [&](int i, int j){ return i * W + j; };
    rep(i,H)rep(j,W)rep(d,4) {
        int ni = i + di[d], nj = j + dj[d];
        if(0 <= ni && ni < H && 0 <= nj && nj < W) {
            G[h(i, j)].push_back({h(ni, nj), 1});
        }
    }

    int s = H * W, t = s + 1;
    for(auto [i, j] : S) G[s].push_back({h(i, j), 0});
    for(auto [i, j] : T) G[h(i, j)].push_back({t, 0});
    cout << bfs(G, s)[t] - 1 << endl;
}