#include <algorithm>
#include <bitset>
#include <climits>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

#define MOD 1000000007
#define MOD2 998244353
#define int long long
#define double long double
#define EPS 1e-9
//#define PI 3.14159265358979

#define rep(i, n) for (int i = 0; i < (int)(n); i++)

using namespace std;

template < typename T >
ostream &operator<<(ostream &os, const vector< T > &A) {
	for (int i = 0; i < A.size(); i++)
		os << A[i] << " ";
	os << endl;
	return os;
}
template <>
ostream &operator<<(ostream &os, const vector< vector< int > > &A) {
	int N = A.size();
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < A[i].size(); j++)
			os << A[i][j] << " ";
		os << endl;
	}
	return os;
}
template < typename T, typename U >
ostream &operator<<(ostream &os, const pair< T, U > &p) {
	os << "(" << p.first << "," << p.second << ")";
	return os;
}

typedef pair< int, int > pii;
typedef long long ll;

struct edge {
	int from, to, d, c, i;
	edge(int _from = 0, int _to = 0, int _d = 0, int _c = 0) {
		from = _from;
		to = _to;
		d = _d;
		c = _c;
	}
	bool operator<(const edge &rhs) const {
		return (d == rhs.d) ? (c < rhs.c) : (d < rhs.d);
	}
};
struct aabb {
	int x1, y1, x2, y2;
	aabb(int x1, int y1, int x2, int y2) : x1(x1), y1(y1), x2(x2), y2(y2) {}
};

typedef vector< edge > edges;
typedef vector< edges > graph;
struct flow {
	int to, cap, rev, cost;
	flow(int to = 0, int cap = 0, int rev = 0, int cost = 0) : to(to), cap(cap), rev(rev), cost(cost) {}
};
typedef vector< vector< flow > > flows;

const int di[4] = {0, -1, 0, 1};
const int dj[4] = {-1, 0, 1, 0};
const int ci[5] = {0, 0, -1, 0, 1};
const int cj[5] = {0, -1, 0, 1, 0};
const ll LINF = LLONG_MAX / 2;
const int INF = INT_MAX / 2;
const double PI = acos(-1);

int pow2(int n) { return 1LL << n; }
template < typename T, typename U >
bool chmin(T &x, const U &y) {
	if (x > y) {
		x = y;
		return true;
	}
	return false;
}
template < typename T, typename U >
bool chmax(T &x, const U &y) {
	if (x < y) {
		x = y;
		return true;
	}
	return false;
}

template < typename A, size_t N, typename T >
void Fill(A (&array)[N], const T &val) {
	fill((T *)array, (T *)(array + N), val);
}
struct initializer {
	initializer() {
		cout << fixed << setprecision(20);
	}
};
initializer _____;
void flowbfs(flows &F, vector< int > &level, int s) {
	level.assign(level.size(), -1);
	queue< int > q;
	level[s] = 0;
	q.push(s);
	while (!q.empty()) {
		int p = q.front();
		q.pop();
		rep(i, F[p].size()) {
			flow &f = F[p][i];
			if (f.cap > 0 && level[f.to] < 0) {
				level[f.to] = level[p] + 1;
				q.push(f.to);
			}
		}
	}
}
int flowdfs(flows &F, vector< int > &level, vector< int > &iter, int v, int t, int c = INT_MAX) {
	if (v == t)
		return c;
	for (int &i = iter[v]; i < F[v].size(); i++) {
		flow &f = F[v][i];
		if (level[v] >= level[f.to] || f.cap == 0)
			continue;
		int c2 = flowdfs(F, level, iter, f.to, t, min(c, f.cap));
		if (c2 > 0) {
			F[f.to][f.rev].cap += c2;
			F[v][i].cap -= c2;
			return c2;
		}
	}
	return 0;
}
ll maxFlow(flows &F, int s, int t) {
	vector< int > level(F.size());
	vector< int > iter(F.size());
	ll flow = 0;
	while (1) {
		flowbfs(F, level, s);
		if (level[t] < 0)
			return flow;
		iter.assign(iter.size(), 0);
		int f;
		while ((f = flowdfs(F, level, iter, s, t, LONG_MAX - 10)) > 0) {
			flow += f;
		}
	}
}
int N, M, K, T, Q, H, W;
signed main() {
	cin >> H >> W;
	vector< string > grid(H);
	rep(i, H) cin >> grid[i];
	flows F(H + W + 2);
	int s = H + W, t = s + 1;
	rep(i, H) rep(j, W) {
		if (grid[i][j] == 'S') {
			F[s].push_back(flow(i, INF, F[i].size()));
			F[i].push_back(flow(s, 0, F[s].size() - 1));
			F[s].push_back(flow(j + H, INF, F[j + H].size()));
			F[j + H].push_back(flow(s, 0, F[s].size() - 1));
		} else if (grid[i][j] == 'T') {
			F[i].push_back(flow(t, INF, F[t].size()));
			F[t].push_back(flow(i, 0, F[i].size() - 1));
			F[j + H].push_back(flow(t, INF, F[t].size()));
			F[t].push_back(flow(j + H, 0, F[j + H].size() - 1));
		} else if (grid[i][j] == 'o') {
			F[i].push_back(flow(j + H, 1, F[j + H].size()));
			F[j + H].push_back(flow(i, 0, F[i].size() - 1));
			F[j + H].push_back(flow(i, 1, F[i].size()));
			F[i].push_back(flow(j + H, 0, F[j + H].size() - 1));
		}
	}
	int ans = maxFlow(F, s, t);
	if (ans >= INF)
		ans = -1;
	cout << ans << endl;
	return 0;
}

Measured memory_bytes: 5020