#include <iostream>
#include <algorithm>
#include <numeric>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <iomanip>
#include <functional>
#include <bitset>
#include <cstdio>
#include <cmath>
#include <cassert>

#ifdef DEBUG
#include "library/Utility/debug.cpp"
#else
#define debug(...)
#endif

#define rep(i,n) for(int i=0;i<(n);++i)
#define EL '\n'
#define print(i) std::cout << (i) << '\n'
#define all(v) (v).begin(), (v).end()
using lnt = long long;
constexpr lnt INF = 2e18;
/*-*/

using namespace std;
template< typename flow_t >
struct Dinic {
  const flow_t INF;

  struct edge {
    int to;
    flow_t cap;
    int rev;
    bool isrev;
    int idx;
  };

  vector< vector< edge > > graph;
  vector< int > min_cost, iter;

  Dinic(int V) : INF(numeric_limits< flow_t >::max()), graph(V) {}

  void add_edge(int from, int to, flow_t cap, int idx = -1) {
    graph[from].emplace_back((edge) {to, cap, (int) graph[to].size(), false, idx});
    graph[to].emplace_back((edge) {from, 0, (int) graph[from].size() - 1, true, idx});
  }

  bool bfs(int s, int t) {
    min_cost.assign(graph.size(), -1);
    queue< int > que;
    min_cost[s] = 0;
    que.push(s);
    while(!que.empty() && min_cost[t] == -1) {
      int p = que.front();
      que.pop();
      for(auto &e : graph[p]) {
        if(e.cap > 0 && min_cost[e.to] == -1) {
          min_cost[e.to] = min_cost[p] + 1;
          que.push(e.to);
        }
      }
    }
    return min_cost[t] != -1;
  }

  flow_t dfs(int idx, const int t, flow_t flow) {
    if(idx == t) return flow;
    for(int &i = iter[idx]; i < graph[idx].size(); i++) {
      edge &e = graph[idx][i];
      if(e.cap > 0 && min_cost[idx] < min_cost[e.to]) {
        flow_t d = dfs(e.to, t, min(flow, e.cap));
        if(d > 0) {
          e.cap -= d;
          graph[e.to][e.rev].cap += d;
          return d;
        }
      }
    }
    return 0;
  }

  flow_t max_flow(int s, int t) {
    flow_t flow = 0;
    while(bfs(s, t)) {
      iter.assign(graph.size(), 0);
      flow_t f = 0;
      while((f = dfs(s, t, INF)) > 0) flow += f;
    }
    return flow;
  }

  void output() {
    for(int i = 0; i < graph.size(); i++) {
      for(auto &e : graph[i]) {
        if(e.isrev) continue;
        auto &rev_e = graph[e.to][e.rev];
        cout << i << "->" << e.to << " (flow: " << rev_e.cap << "/" << e.cap + rev_e.cap << ")" << endl;
      }
    }
  }
};

int main() {
	int h,w;
	std::cin >> h >> w;
	std::vector<std::string> g(h);
	rep(i,h) std::cin >> g[i];
	std::vector<std::vector<int> > X(h),Y(w);
	int sx,sy,tx,ty;
	rep(i,h) {
		rep(j,w) {
			if(g[i][j]=='o'||g[i][j]=='S'||g[i][j]=='T') {
				if(g[i][j]=='S') {
					sx=i; sy=j;
				}
				if(g[i][j]=='T') {
					tx=i; ty=j;
				}
				X[i].emplace_back(j);
				Y[j].emplace_back(i);
			}
		}
	}
	if(sx==tx||sy==ty) {
		print(-1);
		return 0;
	}
	auto enc = [&] (int i, int j) {
		return i*w+j;
	};
	debug(sx,sy,tx,ty);
	Dinic<int> flow(2*h*w);
	rep(i,h) {
		for(auto y1:X[i]) for(auto y2:X[i]) {
			if(y1==y2) continue;
			flow.add_edge(enc(i,y1),h*w+enc(i,y2),1);
		}
	}
	rep(i,w) {
		for(auto x1:Y[i]) for(auto x2:Y[i]) {
			if(x1==x2) continue;
			flow.add_edge(enc(x1,i),h*w+enc(x2,i),1);
		}
	}
	rep(i,h) rep(j,w) flow.add_edge(enc(i,j)+h*w,enc(i,j),1);
	print(flow.max_flow(enc(sx,sy),enc(tx,ty)+h*w));
}


Measured memory_bytes: 102144