// see https://github.com/LumaKernel/vimfiles/tree/master/snippets/cp-cpp/temp.snip
/// --- .lumrc Template {{{ ///
#if 0
#define assert(...)
#endif
#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using P = tuple<ll, ll>;
using P3 = tuple<ll, ll, ll>;
using VI = vector<int>;
using VL = vector<ll>;
using VVI = vector<VI>;
using VVL = vector<VL>;
using VP = vector<P>;
using VS = vector<string>;

#define omajinai ios::sync_with_stdio(false);cin.tie(0)

#define FOR(i,a,b) for(int i=int(a);i<int(b);++i)
#define FORI(i,a,b) for(int i=int(a);i<=int(b);++i)
#define REP(i,n) FOR(i,0,n)
#define REPI(i,n) FORI(i,0,n)
#define RFOR(i,a,b) for(int i=int(b)-1;i>=int(a);--i)
#define RFORI(i,a,b) for(int i=int(b);i>=int(a);--i)
#define RREP(i,n) RFOR(i,0,n)
#define RREPI(i,n) RFORI(i,0,n)

#define ALL(a) (a).begin(),(a).end()
#define UNIQUE(a) (a).erase(unique(ALL(a)),(a).end())
#define PB push_back
#define EACH(i,c) REP(i,(c).size())
#define REACH(i,c) RREP(i,(c).size())
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort(ALL(c))

#define BR cout<<"\n";

#ifdef DEBUG
#define dump(...) cerr<<"["<<__LINE__<< "] "<<#__VA_ARGS__<<" = "<<make_tuple(__VA_ARGS__)<<"\n";
#else
#define dump(...)
#endif

#define YES(x) cout<<((x)?"YES":"NO")<<"\n";
#define Yes(x) cout<<((x)?"Yes":"No")<<"\n";
#define yes(x) cout<<((x)?"yes":"no")<<"\n";

inline int omajinai_int_in(){omajinai;int n;cin>>n;return n;}
inline ll omajinai_ll_in(){omajinai;ll n;cin>>n;return n;}
inline string omajinai_string_in(){omajinai;string n;cin>>n;return n;}
inline int int_in(){int n;cin>>n;return n;}
inline ll ll_in(){ll n;cin>>n;return n;}
inline string string_in(){string n;cin>>n;return n;}
#define oini omajinai_int_in()
#define oinl omajinai_ll_in()
#define oins omajinai_string_in()
#define ini int_in()
#define inl ll_in()
#define ins string_in()

#define isInside(y,x) (0<=(y)&&(y)<h&&0<=(x)&&(x)<w)

#define fi(x) (get<0>(x))
#define se(x) (get<1>(x))
#define th(x) (get<2>(x))
#define fo(x) (get<3>(x))
#define fif(x) (get<4>(x))

template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) { o << '{'; EACH(i, v) o << v[i] << (i != v.size()-1 ? ", " : ""); o << "}";  return o; }

template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream &, tuple<T...> const &){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream & os, tuple<T...> const & t){ os << (n==0?"":", ") << get<n>(t); _ot<n+1>(os, t); }
template<class...T> ostream & operator<<(ostream & os, tuple<T...> const & t){ _ot<0>(os, t); return os; }

template <typename T> inline void smax(T &a, T b) { a = a > b ? a : b; }
template <typename T> inline void smin(T &a, T b) { a = a < b ? a : b; }

constexpr double PI = acos(-1);

/// }}}--- ///

constexpr int INF = 1e9+1;
constexpr ll LINF = 1e18+1;
constexpr int MOD = 1e9+7;

/// --- Max Flow with FordFulkerson Library {{{ ///

// Ford-Fulkerson
// O(FV)
template<typename T>
struct MaxFlow {
  struct Edge{
    int to; T cap; int rev;
    Edge(int to, T cap, int rev): to(to), cap(cap), rev(rev) {}
  };
  int n;
  vector<vector<Edge> > g; // direcrted
  ll inf;
  MaxFlow(int n, ll inf): n(n), g(n), inf(inf) {}
  void addEdge(int from, int to, T cap) {
    // cap >= 0
    g[from].emplace_back(to, cap, g[to].size());
    g[to].emplace_back(from, 0, g[from].size()-1);
  }
  ll solve(int s, int t) {
    ll flow = 0;
    while(1) {
      VI used(n, 0);
      ll x = dfs(used, s, t, inf);
      if(x == 0) break;
      flow += x;
      if(flow >= inf) return inf;
    }
    return flow;
  }
  private:
  T dfs(VI &used, int v, int t, T m) {
    if(v == t) return m;
    used[v] = 1;
    for(Edge &edge : g[v]) if(!used[edge.to] && edge.cap > 0) {
      ll d = dfs(used, edge.to, t, min(m, edge.cap));
      if(d == 0) continue; ////
      edge.cap -= d;
      g[edge.to][edge.rev].cap += d;
      return d;
    }
    return 0;
  }
};

/// ---}}} ///

int h=oini, w=ini;
int n = h * w;
MaxFlow<int> ecasdqina(n * 2, INF);
string f[110];
int s, t;
void noel(int p1, int i, int j) {
  int p2 = i + j * h;
  if(f[i][j] == 'S') {
    return;
  }
  if(p1 == p2) return;
  ecasdqina.addEdge(p1 + n, p2, INF);
}

// V = 1e4
// F = 1e4
int main() {
  REP(i, h) cin >> f[i];
  REP(i, h) REP(j, w) if(f[i][j] != '.') {
    int p1 = i + j * h;
    if(f[i][j] == 'T') {
      t = p1;
      continue;
    }
    if(f[i][j] == 'S') {
      s = p1 + n;
    }
    ecasdqina.addEdge(p1, p1 + n, 1);
    REP(ii, h) if(ii != i && f[ii][j] != '.') {
      noel(p1, ii, j);
    }
    REP(jj, w) if(jj != j && f[i][jj] != '.') {
      noel(p1, i, jj);
    }
  }
  dump(s,t);
  ll ans = ecasdqina.solve(s, t);
  if(ans >= INF) ans = -1;
  cout << ans << endl;
}



Measured memory_bytes: 65024