#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 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];
  }
};

template <typename C, typename D>
C max_flow(Graph<C, D> &g, int s, int t) {
  const int n = g.n;

  C flow = 0;
  vector<int> used(n);
  int ui = 0;
  function<C(int, int, C)> dfs = [&](int v, int t, C f) {
    if (v == t) return f;
    used[v] = ui;
    for (int i = 0; i < g[v].size(); i++) {
      auto &e = g[v][i];
      if (used[e.to] == ui || e.cap == 0) continue;
      int d = dfs(e.to, t, min(f, e.cap));
      if (d == 0) continue;
      e.cap -= d;
      g[e.to][e.rev].cap += d;
      return d;
    }
    return 0;
  };
  while (true) {
    ui++;
    int f = dfs(s, t, numeric_limits<C>::max());
    if (f == 0) return flow;
    flow += f;
  }
}

void solve() {
  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;
  }
  Graph<int, int> g(h + w + 2);
  int s = 0;
  int t = h + w + 1;
  rep(i, h) rep(j, w) {
    if (a[i][j] == 'o') {
      int u = 1 + i;
      int v = 1 + h + j;
      g.add_edge(u, v);
      g.add_edge(v, u);
    }
  }
  g.add_edge(0, 1 + sx, INF);
  g.add_edge(0, 1 + h + sy, INF);
  g.add_edge(1 + tx, t, INF);
  g.add_edge(1 + h + ty, t, INF);
  int ans = max_flow(g, s, t);
  cout << ans << endl;
}


Measured memory_bytes: 4160