#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <cmath>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <iostream>
#include <random>
#include <map>
#include <iomanip>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
#include <cassert>
#include <fstream>
#include <unordered_map>
#include <cstdlib>
#include <complex>
#include <cctype>
#include <bitset>
using namespace std;

using ll = long long;
using vll = vector<ll>;
using pll = pair<ll, ll>;
using qll = queue<ll>;
using vb = vector<bool>;
using mll = map<ll, ll>;
using sll = stack<ll>;
#define REP(i,n) for(ll i(0);(i)<(n);(i)++)
#define rep(i,n) for(ll i(0);(i)<(n);(i)++)
#define ALL(a) a.begin(), a.end()
#define enld endl //* missspell check
const ll INF = 1LL << 60;
ll H, W;
vector<string> S;


struct edgeForFlow{ll to, cap, rev; }; //! cap: may change; rev: pointer in G[to]

void addEdgeForFlow(vector<vector<edgeForFlow>> &G, ll from, ll to, ll cap){
    G[from].push_back((edgeForFlow){ to, cap,  (ll) G[to].size()});
    G[to].push_back((edgeForFlow) { from, 0, (ll) G[from].size()-1});
}

ll dfsFordFulkson(vector<vector<edgeForFlow>> &G, vb &checked, ll v, ll t, ll f){
    //* v: current vertex, t: sink, f: DELTA of this path. (No need for source)
    if(v == t) return f;
    checked[v] = true;
    REP(i, G[v].size()){
        edgeForFlow &e = G[v][i];
        if(!checked[e.to] && e.cap > 0){
            ll d = dfsFordFulkson(G, checked, e.to, t, min(f, e.cap));
            if(d > 0){
                e.cap -= d;
                G[e.to][e.rev].cap += d;
                return d;
            }
        }
    }
    return 0; //* if no valid outgoing edges
}

ll maxFlowFordFulkson(vector<vector<edgeForFlow>> &G, ll s, ll t){
    vb checked(G.size());
    ll flow = 0;
    for(;;){
        fill(ALL(checked), false);
        ll f = dfsFordFulkson(G, checked, s, t, INF);
        if(f == 0) 
            return flow;
        flow += f;
    }
}

void bfsDinic(vector<vector<edgeForFlow>> &G, vll &level, ll s){
    fill(ALL(level), -1);
    queue<ll> que;
    level[s] = 0;
    que.push(s);
    while(!que.empty()){
        ll v = que.front(); que.pop();
        for(ll i=0; i< G[v].size(); i++){
            edgeForFlow &e = G[v][i];
            if(e.cap > 0 && level[e.to] < 0){
                level[e.to] = level[v] + 1;
                que.push(e.to);
            }
        }
    }
}

ll dfsDinic(vector<vector<edgeForFlow>> &G, vll &level, vll &iter, ll v, ll t, ll f){
    //? iter: record where have been searched?
    //* v: current vertex, t: sink, f: DELTA of this path. (No need for source)
    if(v == t) return f;
    for( ll &i = iter[v]; i < G[v].size(); i++){
        edgeForFlow &e = G[v][i];
        if( e.cap > 0 && level[v] < level[e.to]){
            ll d = dfsDinic(G, level, iter, e.to, t, min(f, e.cap));
            if(d > 0){
                e.cap -= d;
                G[e.to][e.rev].cap += d;
                return d;
            }
        }
    }
    return 0; //* if no valid outgoing edges
}

ll maxFlowDinic(vector<vector<edgeForFlow>> &G, ll s, ll t){
    vll level(G.size()), iter(G.size());
    ll flow = 0;
    for(;;){
        bfsDinic(G, level, s);
        if(level[t] < 0)//* sink t is not reachable from s on current residual graph
            return flow;
        fill(ALL(iter), 0);
        ll f;
        while((f = dfsDinic(G, level, iter, s, t, INF)) > 0){
            flow += f;
        }
    }
}

int main(){
    cin >> H >> W;
    S.resize(H);
    REP(i, H){
        cin>> S[i];
    }
    vector<vector<edgeForFlow>> G(H+W+2);
    //* G[H+W]: S, G[H+W+1]: T
    REP(i, H){
        REP(j, W){
            if(S[i][j]=='.')
                continue;
            if(S[i][j]=='o'){
                addEdgeForFlow(G, i, j+H, 1);
                addEdgeForFlow(G, j+H, i, 1);
            }
            else if(S[i][j] == 'S'){
                addEdgeForFlow(G, H+W, i, H*W);
                addEdgeForFlow(G, H+W, j+H, H*W);
            }
            else{ //*S[i][j] == 'T'
                addEdgeForFlow(G, i, H+W+1, H*W);
                addEdgeForFlow(G, j+H, H+W+1, H*W);
            }
        }
    }
    ll flow = 0;
    flow = maxFlowDinic(G, H+W, H+W+1);
    if(flow >= H*W){
        cout << -1<<endl;
    }
    else{
        cout << flow << endl;
    }
    return 0;
}


Measured memory_bytes: 1536