#include <bits/stdc++.h>
 
using namespace std;
 
#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl;
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}
typedef long long ll;
#define int ll
 
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep1(i,n) for(int i=1;i<=(n);i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a = b; return 1; } return 0; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const long double pi = 3.1415926535897932384626433832795028841971L;
#define Sp(p) cout<<setprecision(25)<< fixed<<p<<endl;
//int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
//int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
vi dx = {1, 0, -1, 0}, dy = {0, 1, 0, -1};
vi dx2 = { 1,1,0,-1,-1,-1,0,1 }, dy2 = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
//const ll MOD = 1000000007;
const ll MOD = 998244353;
// #define mp make_pair
//#define endl '\n'



// 辺を表す構造体 {行先、容量、逆辺}
struct edge { int to; ll cap; int rev; };

class Dinic {
public:
	int n;
	vector< vector<edge> > G; //グラフの隣接リスト表現
	vl level; //sからの距離
	vi iter; //どこまで調べ終わったか


	Dinic(int n) :n(n), level(n), iter(n), G(n) {}

	//fromからtoへ向かう容量capの辺をグラフに追加する
	void add_edge(int from, int to, ll cap) {
		edge a;
		a.to = to; a.cap = cap; a.rev = G[to].size();
		G[from].push_back(a);
		a.to = from; a.cap = 0; a.rev = G[from].size() - 1;
		G[to].push_back(a);
	}

	//sからの最短距離をBFSで計算する
	void bfs(int s) {
		fill(level.begin(), level.end(), -1);
		queue<int> que;
		level[s] = 0;
		que.push(s);
		while (!que.empty()) {
			int v = que.front(); que.pop();
			for (int i = 0; i < G[v].size(); i++) {
				edge &e = G[v][i];
				if (e.cap > 0 && level[e.to] < 0) {
					level[e.to] = level[v] + 1;
					que.push(e.to);
				}
			}
		}
	}

	//増加パスをDFSで探す
	ll dfs(int v, int t, ll f) {
		if (v == t) return f;
		for (int &i = iter[v]; i < G[v].size(); i++) {
			edge &e = G[v][i];
			if (e.cap > 0 && level[v] < level[e.to]) {
				ll d = dfs(e.to, t, min(f, e.cap));
				if (d > 0) {
					e.cap -= d;
					G[e.to][e.rev].cap += d;
					return d;
				}
			}
		}
		return 0;
	}

	//sからtへの最大流を調べる
	ll max_flow(int s, int t) {
		ll flow = 0;
		for (;;) {
			bfs(s);
			if (level[t] < 0) return flow;
			fill(iter.begin(), iter.end(), 0);
			ll f;
			while ((f = dfs(s, t, INF)) > 0) {
				flow += f;
			}
		}
	}
};

signed main() {
    fio();
    int h, w;
    cin >> h >> w;
    Dinic dinic(h * w + 2);
    rep (i, h) {
        rep (j, w) {
            char c;
            cin >> c;
            if (c == 'o') {
                dinic.add_edge(i + 1, h + j + 1, 1);
                dinic.add_edge(h + j + 1, i + 1, 1);
            }
            else if (c == 'S') {
                dinic.add_edge(0, i + 1, INF);
                dinic.add_edge(0, h + j + 1, INF);
            }
            else if (c == 'T') {
                dinic.add_edge(i + 1, h + w + 1, INF);
                dinic.add_edge(h + j + 1, h + w + 1, INF);
            }
        }
    }

    ll ans = dinic.max_flow(0, h + w + 1);
    if (ans >= INF / 2) {
        ans = -1;
    }
    cout << ans << endl;
}

Measured memory_bytes: 1920