#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <iomanip>
#include <sys/time.h>
#include <tuple>
#include <random>
using namespace std;

#define endl '\n'
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define UNIQ(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef complex<double> comp;
typedef vector< vector<ld> > matrix;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
	size_t seed = hash<T>()(x.first);
	return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};
const int inf = 1e9 + 9;
const ll mod = 1e9 + 7;
const double eps = 1e-8;
const double pi = acos(-1);

int h, w;
string a[110];

const int MAX = 20100;
struct edge {
    int to, cap, rev;
};

vector<edge> G[MAX];
int level[MAX];
int iter[MAX];

void add_edge(int from, int to, int cap) {
    G[from].push_back((edge){to, cap, (int)G[to].size()});
    G[to].push_back((edge){from, 0, (int)G[from].size()-1});
}

void bfs(int s) {
    memset(level, -1, sizeof(level));
    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 and level[e.to] < 0) {
                level[e.to] = level[v] + 1;
                que.push(e.to);
            }
        }
    }
}
int dfs(int v, int t, int 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 and level[v] < level[e.to]) {
            int 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;
}

int dinic(int s, int t) {
    int flow = 0;
    while (true) {
        bfs(s);
        if (level[t] < 0) return flow;
        memset(iter, 0, sizeof(iter));
        int f;
        while ((f = dfs(s, t, inf)) > 0) {
            flow += f;
        }
    }
}

int solve() {
    P sp, tp;
    int s = 2*h*w, t = 2*h*w+1;
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            if (a[i][j] == 'S') {
                sp = make_pair(i, j);
                for (int k = 0; k < h; k++) {
                    if (a[k][j] == 'T')
                        return -1;
                    if (a[k][j] == 'o') {
                        add_edge(s, 2*(k*w+j), 1);
                    }
                }
                for (int k = 0; k < w; k++) {
                    if (a[i][k] == 'T')
                        return -1;
                    if (a[i][k] == 'o') {
                        add_edge(s, 2*(i*w+k), 1);
                    }
                }
            }
        }
    }

    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            if (a[i][j] == 'o') {
                int id = 2*(i*w+j)+1;
                add_edge(id-1, id, 1);
                for (int k = 0; k < h; k++) {
                    if (k != i && a[k][j] == 'o') {
                        add_edge(id, 2*(k*w+j), 1);
                    } else if (a[k][j] == 'T') {
                        add_edge(id, t, 1);
                    }
                }
                for (int k = 0; k < w; k++) {
                    if (k != j && a[i][k] == 'o') {
                        add_edge(id, 2*(i*w+k), 1);
                    } else if (a[i][k] == 'T') {
                        add_edge(id, t, 1);
                    }
                }
            }
        }
    }

    return dinic(s, t);
}

void input() {
    cin >> h >> w;
    for (int i = 0; i < h; i++) cin >> a[i];
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);

    input();
    cout << solve() << endl;
}


Measured memory_bytes: 62592