#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#include "bits/stdc++.h" // define macro "/D__MAI"

using namespace std;
typedef unsigned int uint;
typedef long long int ll;
typedef unsigned long long int ull;

#define debugv(v) printf("L%d %s => ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;
#define debugm(m) printf("L%d %s is..\n",__LINE__,#m);for(auto v:m){for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) printf("L%d %s is => ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;
#define debugaa(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[x][y]<<" ";}cout<<endl;}
#define debugaar(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}
#define ALL(v) (v).begin(),(v).end()
#define repeat(l) for(auto cnt=0;cnt<(l);++cnt)
#define upto(l,r) for(auto cnt=l;cnt<=r;++cnt)
#define downto(r,l) for(auti cnt=r;cnt>=l;--cnt)
#define BIGINT 0x7FFFFFFF
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
template<typename T1, typename T2>
ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << "(" << p.first << ":" << p.second << ")"; return o; }

#define TIME chrono::system_clock::now()
#define MILLISEC(t) (chrono::duration_cast<chrono::milliseconds>(t).count())
namespace {
    std::chrono::system_clock::time_point ttt;
    void tic() { ttt = TIME; }
    void toc() { fprintf(stderr, "TIME : %lldms\n", MILLISEC(TIME - ttt)); }
    std::chrono::system_clock::time_point tle = TIME;
#ifdef __MAI
    void safe_tle(int msec) { assert(MILLISEC(TIME - tle) < msec); }
#else
#define safe_tle(k) ;
#endif
}

#ifdef __MAI //_getchar_nolock
#define getchar_unlocked getchar
#endif
namespace {
#define isvisiablechar(c) (0x33<=(c)&&(c)<=0x7E)
    class MaiScanner {
    public:
        template<typename T>
        void input_integer(T& var) {
            var = 0;
            T sign = 1;
            int cc = getchar_unlocked();
            for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc&&cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var*sign;
        }
        inline int c() { return getchar_unlocked(); }
        inline MaiScanner& operator>>(int& var) {
            input_integer<int>(var);
            return *this;
        }
        inline MaiScanner& operator>>(long long& var) {
            input_integer<long long>(var);
            return *this;
        }
        inline MaiScanner& operator>>(string& var) {
            int cc = getchar_unlocked();
            for (; !isvisiablechar(cc); cc = getchar_unlocked());
            for (; isvisiablechar(cc); cc = getchar_unlocked())
                var.push_back(cc);
        }
    };
}
MaiScanner scanner;

class Flow {
public:
    size_t n;
    struct Arrow {
        int from, to;
        int w_max;
        int cap;

        Arrow(int from = 0, int to = 0, int w = 1) :from(from), to(to), w_max(w), cap(w) {}
        bool operator<(const Arrow& a) const { return (from<a.from) | (to<a.to) | (w_max<a.w_max) | (cap<a.cap); }
        bool operator==(const Arrow& a) const { return (from == a.from) && (to == a.to) && (w_max == a.w_max) && (cap == a.cap); }
    };
    vector<vector<int>> vertex_to;
    vector<vector<int>> vertex_from;
    vector<Arrow> arrow;

    Flow(int n, int m = 5010) :n(n), vertex_to(n), vertex_from(n) { arrow.reserve(m); }

    void connect(int from, int to, int left) {
        vertex_to[from].push_back(arrow.size()); // toto
        vertex_from[to].push_back(arrow.size()); // fromfrom
        arrow.emplace_back(from, to, left);
    }
    size_t degree(int v) {
        return vertex_to[v].size() + vertex_from[v].size();
    }
    size_t degree_in(int v) {
        return vertex_from[v].size();
    }
    size_t degree_out(int v) {
        return vertex_to[v].size();
    }
};



int _dinic_path_dfs(Flow& flow, vector<int>& result, vector<int>& flag, const vector<int>& dist, int u, int i_sink, int mini) {
    // TODO: 経路再利用
    if (i_sink == u) return mini;
    if (flag[u]) return -1;
    flag[u] = true;

    int sumw = 0;
    bool term = true;
    for (int e : flow.vertex_to[u]) {
        Flow::Arrow& a = flow.arrow[e];
        if (a.w_max > 0 && dist[u]>dist[a.to]) {
            int w;
            if (mini < 0)
                w = a.w_max;
            else
                w = min(a.w_max, mini);

            w = _dinic_path_dfs(flow, result, flag, dist, a.to, i_sink, w);
            if (w == -1) continue;
            a.w_max -= w;
            result[a.to] += w;

            sumw += w;
            mini -= w;
            term = false;
            flag[u] = false; // TODO: 末尾では? 

            if (mini == 0) return term ? -1 : sumw;
        }
    }
    for (int e : flow.vertex_from[u]) {
        Flow::Arrow& a = flow.arrow[e];
        if (a.cap>a.w_max && dist[u]>dist[a.from]) {
            int w;
            if (mini < 0)
                w = a.cap - a.w_max;
            else
                w = min(a.cap - a.w_max, mini);

            w = _dinic_path_dfs(flow, result, flag, dist, a.from, i_sink, w);
            if (w == -1) continue;
            a.w_max += w;
            result[a.to] -= w;

            sumw += w;
            mini -= w;
            term = false;
            flag[u] = false;
            if (mini == 0) return term ? -1 : sumw;
        }
    }
    return term ? -1 : sumw;
}

// flowは書き換えられる．
void dinic(Flow &flow, vector<int>& result, int i_source, int i_sink) {
    assert(i_source != i_sink);

    result.resize(flow.n);

    int distbegin = 0;
    vector<int> dist(flow.n);
    queue<int> q;
    vector<int> flag(flow.n);
    for (int distbegin = 0; ; distbegin += flow.n) {

        q.emplace(i_sink); // bfsはsinkからsourceへの距離を計算．
        dist[i_sink] = distbegin + 1;
        while (!q.empty()) {
            int v = q.front();
            q.pop();
            for (int ie : flow.vertex_from[v]) {
                const Flow::Arrow& e = flow.arrow[ie];
                if (0<e.w_max && dist[e.from] <= distbegin) {
                    dist[e.from] = dist[v] + 1;
                    q.emplace(e.from);
                }
            }
            for (int ie : flow.vertex_to[v]) {
                const Flow::Arrow& e = flow.arrow[ie];
                if (e.w_max<e.cap && dist[e.to] <= distbegin) {
                    dist[e.to] = dist[v] + 1;
                    q.emplace(e.to);
                }
            }
        }
        //debugv(dist);
        fill(ALL(flag), false);

        if (dist[i_source] <= distbegin) {
            break;
        }
        else {
            result[i_source] += _dinic_path_dfs(flow, result, flag, dist, i_source, i_sink, -1);
        }
    }

}


int width, height;
int n;

string field[110];

int start, goal;

int main() {
    int i, j, k;
    ll a, b;

    const ll ofs = 2000000000;

    cin >> height >> width;

    repeat(height) {
        cin >> field[cnt];
    }

    int sx, sy, gx, gy;
    for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x) {
            if (field[y][x] == 'S') {
                start = y *width + x;
                sx = x; sy = y;
            }
            else if(field[y][x] == 'T'){
                goal = y *width + x;
                gx = x; gy = y;
            }
        }
    }
    if (sx == gx || sy == gy) {
        cout << -1 << endl;
        return 0;
    }

    n = height*width;

    Flow ff(n*2 + height + width, 5050);

    int t;
    for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x) {
            t = (y*width + x);
            ff.connect(t, n + t, 1);
        }
    }
    for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x) {
            t = (y*width + x);
            if (field[y][x] != '.') {
                ff.connect(n + t, n*2 + y, 101010);
                ff.connect(n*2 + y, t, 101010);
            }
        }
    }
    for (int x = 0; x < width; ++x) {
        for (int y = 0; y < height; ++y) {
            t = (y*width + x);
            if (field[y][x] != '.') {
                ff.connect(n+t, n*2 + height + x, 101010);
                ff.connect(n*2 + height + x, t, 101010);
            }
        }
    }

    vector<int> res;
    dinic(ff, res, n + start, goal);

    cout << res[goal] << endl;


    return 0;
}

Measured memory_bytes: 3876