#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using V = vector<int>;
using Vll = vector<ll>;
using Vld = vector<ld>;
using Vbo = vector<bool>;
using VV = vector<V>;
using VVll = vector<Vll>;
using VVld = vector<Vld>;
using VVbo = vector<Vbo>;
using P = pair<int, int>;
using Pll = pair<ll, ll>;
using Pld = pair<ld, ld>;
#define rep2(i, m, n) for(ll i=int(m); i<int(n); ++i)
#define drep2(i, m, n) for(ll i=int(m)-1; i>=int(n); --i)
#define rep(i, n) rep2(i, 0, n)
#define drep(i, n) drep2(i, n, 0)
#define all(a) a.begin(), a.end()
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
template<typename T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; }
template<typename T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; }
template<typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p) { is >> p.first >> p.second; return is; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
template<typename T> istream &operator>>(istream &is, vector<T> &v) { for (auto &e : v) is >> e; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &v) { for (auto &e : v) os << e << " "; return os; }
template<typename T> inline int count_between(vector<T> &a, T l, T r) { return lower_bound(all(a), r) - lower_bound(all(a), l); } // [l, r)
inline int Log2(ll x) { int k; for (k = 0; x > 0; ++k) x >>= 1; return k; } // number of binary digits
const int INF  = 1<<30;
const ll INFll = 1ll<<62;
const ld EPS   = 1e-10;
const int MOD  = int(1e9)+7;


// struct Node {
//   int i, j, k;
//   Node(int i, int j, int k) : i(i), j(j), k(k) { }
// };


int h, w;
int nid (int i, int j, int k) {
  return (i*w + j)*2 + k;
}


template< typename flow_t >
struct FordFulkerson {
  struct edge {
    int to;
    flow_t cap;
    int rev;
    bool isrev;
    int idx;
  };

  vector< vector< edge > > graph;
  vector< int > used;
  const flow_t INF;
  int timestamp;

  FordFulkerson(int n) : INF(numeric_limits< flow_t >::max()), timestamp(0) {
    graph.resize(n);
    used.assign(n, -1);
  }

  void add_edge(int from, int to, flow_t cap, int idx = -1) {
    graph[from].emplace_back((edge) {to, cap, (int) graph[to].size(), false, idx});
    graph[to].emplace_back((edge) {from, 0, (int) graph[from].size() - 1, true, idx});
  }

  flow_t dfs(int idx, const int t, flow_t flow) {
    if(idx == t) return flow;
    used[idx] = timestamp;
    for(auto &e : graph[idx]) {
      if(e.cap > 0 && used[e.to] != timestamp) {
        flow_t d = dfs(e.to, t, min(flow, e.cap));
        if(d > 0) {
          e.cap -= d;
          graph[e.to][e.rev].cap += d;
          return d;
        }
      }
    }
    return 0;
  }

  flow_t max_flow(int s, int t) {
    flow_t flow = 0;
    for(flow_t f; (f = dfs(s, t, INF)) > 0; timestamp++) {
      flow += f;
    }
    return flow;
  }

  void output() {
    for(int i = 0; i < graph.size(); i++) {
      for(auto &e : graph[i]) {
        if(e.isrev) continue;
        auto &rev_e = graph[e.to][e.rev];
        cout << i << "->" << e.to << " (flow: " << rev_e.cap << "/" << e.cap + rev_e.cap << ")" << endl;
      }
    }
  }
};


int main() {
  cin >> h >> w;
  vector<string> s(h); cin >> s;

  int n = nid(h-1, w-1, 1) + 1;
  FordFulkerson<ll> G(n);

  Vll sid(2), tid(2);
  rep(i, h) rep(j, w) {
    if (s[i][j] == 'S') sid = {i, j};
    if (s[i][j] == 'T') tid = {i, j};
  }

  if (sid[0] == tid[0] || sid[1] == tid[1]) {
    cout << -1 << "\n";
    return 0;
  }

  rep(i, h) rep(j1, w) rep(j2, w) {
    if (j1 == j2 && s[i][j1] == 'o') {
      G.add_edge(nid(i, j1, 0), nid(i, j2, 1), 1);
    }
    if ((s[i][j1] == 'S' || s[i][j1] == 'o') && (s[i][j2] == 'T' || s[i][j2] == 'o')) {
      G.add_edge(nid(i, j1, 1), nid(i, j2, 0), INFll);
    }
  }
  rep(j, w) rep(i1, h) rep(i2, h) {
    if ((s[i1][j] == 'S' || s[i1][j] == 'o') && (s[i2][j] == 'T' || s[i2][j] == 'o')) {
      G.add_edge(nid(i1, j, 1), nid(i2, j, 0), INFll);
    }
  }

  ll ans = G.max_flow(nid(sid[0], sid[1], 1), nid(tid[0], tid[1], 0));
  cout << ans << "\n";
  return 0;
}


Measured memory_bytes: 162816