#include <bits/stdc++.h>
using namespace std;
#define int long long
#define stoi stoll
using pii=pair<int,int>;
#define all(c) begin(c),end(c)
#define rall(c) rbegin(c),rend(c)
#define fore(x,c) for(auto &&x:c)
#define rep(i,a,n) for(int i=a,i##len=(int)(n);i<i##len;++i)
#define rrep(i, a, n) for(int i=(int)(n-1);i>=a;--i)
#define sz(c) ((int)c.size())
#define contains(c,x) (c.find(x)!=end(c))
#define inseg(l,x,r) ((l)<=(x)&&(x)<(r))
#define dump(...)
#define pb push_back
#define _ 0
const signed INF_=1001001001; const long long INF=1001001001001001001LL;
const int DX[9]={0,1,0,-1,1,1,-1,-1,0},DY[9]={-1,0,1,0,-1,1,1,-1,0};
template<class T> ostream& operator<<(ostream &os,const vector<T> &v) {
    for (auto i = begin(v); i != end(v); i++) os<<*i<<(i==end(v)-1?"":" ");return os;}
template<class T> istream& operator>>(istream &is,vector<T> &v) {
    for (auto i = begin(v); i != end(v); i++) is>>*i;return is;}
template<class T,class U> istream& operator>>(istream &is, pair<T,U> &p) {
    is>>p.first>>p.second;return is;}
template<class T, class U> bool chmax(T &a,const U &b){return a<b?a=b,1:0;}
template<class T, class U> bool chmin(T &a,const U &b){return a>b?a=b,1:0;}
template <class T> void psum(T& c) {partial_sum(begin(c), end(c), begin(c));}
template<class T> using heap=priority_queue<T,vector<T>,greater<T>>;
struct before_main_function {
    before_main_function() {
        cin.tie(0); ios::sync_with_stdio(0);
        cout << setprecision(15) << fixed;
        // #define endl "\n"
    }
} before_main_function;
//------------------8<------------------------------------8<--------------------

struct Dinic {
    struct edge { int to, cap, rev; };
    int V;
    vector<vector<edge>> G;
    vector<int> itr, level;

    Dinic(int V) : V(V) { G.assign(V, vector<edge>()); }

    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 add_edge_undirected(int a, int b, int cap) {
        G[a].push_back((edge){b, cap, (int)G[b].size()});
        G[b].push_back((edge){a, cap, (int)(G[a].size() - 1)});
    }

    void bfs(int s) {
        level.assign(V, -1);
        queue<int> q;
        level[s] = 0;
        q.push(s);
        while (!q.empty()) {
            int v = q.front(); q.pop();
            for (auto &e : G[v]) {
                if (e.cap > 0 && level[e.to] < 0) {
                    level[e.to] = level[v] + 1;
                    q.push(e.to);
                }
            }
        }
    }

    int dfs(int v, int t, int f) {
        if (v == t) return f;
        for (int &i = itr[v]; i < G[v].size(); i++) {
            edge &e = G[v][i];
            if (e.cap > 0 && 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 max_flow(int s, int t) {
        int ret = 0, f;
        while (bfs(s), level[t] >= 0) {
            itr.assign(V, 0);
            while ((f = dfs(s, t, INF)) > 0) ret += f;
        }
        return ret;
    }
};

signed main() {
    int H, W;
    cin >> H >> W;
    vector<string> B(H);
    cin >> B;

    Dinic flow(H + W + 2);
    int S = 0, T = 1;
    auto row = [&](int r) { return 2 + r; };
    auto col = [&](int c) { return 2 + H + c; };

    rep(i, 0, H) {
        rep(j, 0, W) {
            if (B[i][j] == 'S') {
                flow.add_edge(S, col(j), INF);
                flow.add_edge(S, row(i), INF);
                flow.add_edge_undirected(row(i), col(j), 1);
            }
            if (B[i][j] == 'T') {
                flow.add_edge(col(j), T, INF);
                flow.add_edge(row(i), T, INF);
                flow.add_edge_undirected(row(i), col(j), 1);
            }
            if (B[i][j] == 'o') {
                flow.add_edge_undirected(row(i), col(j), 1);
            }
        }
    }
    int ans = flow.max_flow(S, T);
    if (ans >= INF) ans = -1;
    cout << ans << endl;
    return (0^_^0);
}



Measured memory_bytes: 896