#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < int(n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
#define reps(i, n) for (int i = 1; i <= int(n); i++)
#define rreps(i, n) for (int i = int(n); i >= 1; i--)
#define repc(i, n) for (int i = 0; i <= int(n); i++)
#define rrepc(i, n) for (int i = int(n); i >= 0; i--)
#define repi(i, a, b) for (int i = int(a); i < int(b); i++)
#define repic(i, a, b) for (int i = int(a); i <= int(b); i++)
#define all(a) (a).begin(), (a).end()
#define bit32(x) (1 << (x))
#define bit64(x) (1ll << (x))
#define sz(v) ((int) v.size())

using namespace std;

using i64 = long long;
using f80 = long double;
using vi32 = vector<int>;
using vi64 = vector<i64>;
using vf80 = vector<f80>;
using vstr = vector<string>;

void yes() { cout << "Yes" << endl; exit(0); }
void no() { cout << "No" << endl; exit(0); }
template <typename T> class pqasc : public priority_queue<T, vector<T>, greater<T>> {};
template <typename T> class pqdesc : public priority_queue<T, vector<T>, less<T>> {};
template <typename T> void amax(T &x, T y) { x = max(x, y); }
template <typename T> void amin(T &x, T y) { x = min(x, y); }
template <typename T> T exp(T x, i64 n, T e = 1) { T r = e; while (n > 0) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; }
template <typename T> istream& operator>>(istream &is, vector<T> &v) { for (auto &x : v) is >> x; return is; }
template <typename T> ostream& operator<<(ostream &os, vector<T> &v) { rep(i, v.size()) { if (i) os << ' '; os << v[i]; } return os; }
void solve(); int main() { ios::sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(16); solve(); return 0; }

template <typename T, typename U>
vector<U> make_vector(T&& n, U&& val) {
  return vector<U>(forward<T>(n), forward<U>(val));
}
template <typename T, typename... Args>
decltype(auto) make_vector(T&& n, Args&&... args) {
  return vector<decltype(make_vector(forward<Args>(args)...))>(forward<T>(n), make_vector(forward<Args>(args)...));
}

const int INF = 1001001001;
const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};

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;
      }
    }
  }
};

template <typename Cap, typename Cost>
struct Graph {
  const Cost INF = numeric_limits<Cost>::max();
  struct Edge {
    int to, rev;
    Cap cap;
    Cost cost;
    Edge(int to, Cap cap, Cost cost, int rev)
      : to(to), cap(cap), cost(cost), rev(rev) {}
  };
  vector<vector<Edge>> g;
  int n;
  Graph(int n) : n(n) {
    g.assign(n, vector<Edge>());
  }
  void add_edge(int v, int u, Cap cap = 1, Cost cost = 0) {
    g[v].emplace_back(u, cap, cost, (int) g[u].size());
    g[u].emplace_back(v, 0, -cost, (int) g[v].size() - 1);
  }
  vector<Edge>& operator[](int x) {
    return g[x];
  }
};

void solve() {
  // {
  //   int h, w;
  //   h = 100;
  //   w = 100;
  //   vstr a(h);
  //   rep(i, h) a[i] = string(w, 'o');
  //   a[0][0] = 'S';
  //   a[h-1][w-1] = 'T';
  //   cout << h << " " << w << endl;
  //   rep(i, h) cout << a[i] << endl;
  //   return;
  // }
  int h, w;
  cin >> h >> w;
  vstr a(h);
  cin >> a;
  int sx, sy, tx, ty;
  rep(i, h) rep(j, w) {
    if (a[i][j] == 'S') sx = i, sy = j;
    if (a[i][j] == 'T') tx = i, ty = j;
  }
  if (sx == tx || sy == ty) {
    cout << -1 << endl;
    return;
  }
  auto id = [&](int x, int y) {
    return x * w + y;
  };
  FordFulkerson<int> g(h * w * 2);
  rep(i, h) rep(j, w) if (a[i][j] != '.') {
    int u = id(i, j);
    rep(k, h) if (k != i && a[k][j] != '.') {
      int v = id(k, j) + h * w;
      g.add_edge(u, v, 1);
    }
    rep(k, w) if (k != j && a[i][k] != '.') {
      int v = id(i, k) + h * w;
      g.add_edge(u, v, 1);
    }
  }
  rep(i, h) rep(j, w) if (a[i][j] != '.') {
    int u = id(i, j) + h * w;
    int v = id(i, j);
    int t = a[i][j] == 'o' ? 1 : h * w * 2;
    g.add_edge(u, v, t);
  }
  int ans = g.max_flow(id(sx, sy), id(tx, ty));
  cout << ans << endl;
}


Measured memory_bytes: 107904