#include <bits/stdc++.h>

                                            //    #include <boost/multiprecision/cpp_int.hpp>
 
                               	       #define int long long
                                                #define inf  1000000007
                                              #define pa pair<int,int>
                                               #define pad pair<double,double>
                                                #define ll long long
                                                #define pal pair<double,double>
                                                #define ppap pair<pa,int>
                                          #define PI 3.14159265358979323846
                                                #define paa pair<pa,pa>
                                                #define  mp make_pair
                                                #define  pb push_back
                                                #define EPS (1e-10)
                                                #define equals(a,b) (fabs((a)-(b))<EPS)
                                            //    #define double long double
        int dx[4]={0,-1,0,1};
        int dy[4]={1,0,-1,0};
                                                using namespace std;
                                       			class pa3{
                                                	public:
                                                	int x,y,z;
                                                	pa3(int x=0,int y=0,int z=0):x(x),y(y),z(z) {}
                                                	bool operator < (const pa3 &p) const{
                                                		if(x!=p.x) return x<p.x;
                                                		if(y!=p.y) return y<p.y;
                                                		 return z<p.z;
                                                		//return x != p.x ? x<p.x: y<p.y;
                                                	}
                                       				bool operator > (const pa3 &p) const{
                                                		if(x!=p.x) return x>p.x;
                                                		if(y!=p.y) return y>p.y;
                                                		 return z>p.z;
                                                		//return x != p.x ? x<p.x: y<p.y;
                                                	}
                                                	bool operator == (const pa3 &p) const{
                                                		return x==p.x && y==p.y && z==p.z;
                                                	}
                                                		bool operator != (const pa3 &p) const{
                                                			return !( x==p.x && y==p.y && z==p.z);
                                                	}
                                                
                                                };
                                                
                                                class pa4{
                                                	public:
                                                	int x;
                                                	int y,z,w;
                                                	pa4(int x=0,int y=0,int z=0,int w=0):x(x),y(y),z(z),w(w) {}
                                                	bool operator < (const pa4 &p) const{
                                                		if(x!=p.x) return x<p.x;
                                                		if(y!=p.y) return y<p.y;
                                                		if(z!=p.z)return z<p.z;
                                                		return w<p.w;
                                                		//return x != p.x ? x<p.x: y<p.y;
                                                	}
                                                	bool operator > (const pa4 &p) const{
                                                		if(x!=p.x) return x>p.x;
                                                		if(y!=p.y) return y>p.y;
                                                		if(z!=p.z)return z>p.z;
                                                		return w>p.w;
                                                		//return x != p.x ? x<p.x: y<p.y;
                                                	}
                                                	bool operator == (const pa4 &p) const{
                                                		return x==p.x && y==p.y && z==p.z &&w==p.w;
                                                	}
                                                	
                                                	bool operator != (const pa4 &p) const{
                                                		return !(x==p.x && y==p.y && z==p.z &&w==p.w);
                                                	}
                                                		
                                                
                                                };
                                                class pa2{
                                                	public:
                                                	int x,y;
                                                	pa2(int x=0,int y=0):x(x),y(y) {}
                                                	pa2 operator + (pa2 p) {return pa2(x+p.x,y+p.y);}
                                                	pa2 operator - (pa2 p) {return pa2(x-p.x,y-p.y);}
                                                	bool operator < (const pa2 &p) const{
                                                		return x!= p.x ? x<p.x: y<p.y;
                                                	}
                                                	bool operator > (const pa2 &p) const{
                                                		return x != p.x ? x>p.x: y>p.y;
                                                	}
                                                	bool operator == (const pa2 &p) const{
                                                		return abs(x-p.x)==0 && abs(y-p.y)==0;
                                                	}
                                                	bool operator != (const pa2 &p) const{
                                                		return !(abs(x-p.x)==0 && abs(y-p.y)==0);
                                                	}
                                                		
                                                
                                                };
                                                
                                              
                                                
                                                       #define ppa pair<int,pas>
                                                class Point{
                                                	public:
                                                	double x,y;
                                                	Point(double x=0,double y=0):x(x),y(y) {}
                                                	Point operator + (Point p) {return Point(x+p.x,y+p.y);}
                                                	Point operator - (Point p) {return Point(x-p.x,y-p.y);}
                                                	Point operator * (double a) {return Point(x*a,y*a);}
                                                	Point operator / (double a) {return Point(x/a,y/a);}
                                                	double absv() {return sqrt(norm());}
                                                	double norm() {return x*x+y*y;}
                                                	bool operator < (const Point &p) const{
                                                		return x != p.x ? x<p.x: y<p.y;
                                                	}
                                                	bool operator == (const Point &p) const{
                                                		return fabs(x-p.x)<EPS && fabs(y-p.y)<EPS;
                                                	}
                                                };
                                                typedef Point Vector;
                                         #define pl pair<int,pas>
                                                struct Segment{
                                                Point p1,p2;
                                                };
                                                 double dot(Vector a,Vector b){
                                                	return a.x*b.x+a.y*b.y;
                                                }
                                                double cross(Vector a,Vector b){
                                                	return a.x*b.y-a.y*b.x;
                                                }
                                            
                    bool parareru(Point a,Point b,Point c,Point d){
                    //	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
                    	return abs(cross(a-b,d-c))<EPS;
                    }
                    double distance_ls_p(Point a, Point b, Point c) {
                      if ( dot(b-a, c-a) < EPS ) return (c-a).absv();
                      if ( dot(a-b, c-b) < EPS ) return (c-b).absv();
                      return abs(cross(b-a, c-a)) / (b-a).absv();
                    }
                    bool is_intersected_ls(Segment a,Segment b) {
                    	if(a.p1==b.p1||a.p2==b.p1||a.p1==b.p2||a.p2==b.p2) return 1;
                    	if(parareru((a.p2),(a.p1),(a.p1),(b.p2))&&parareru((a.p2),(a.p1),(a.p1),(b.p1))){
                    //		cout<<"sss"<<endl;
                    		if(dot(a.p1-b.p1,a.p1-b.p2)<EPS) return true;
                    		if(dot(a.p2-b.p1,a.p2-b.p2)<EPS) return true;
                    		if(dot(a.p1-b.p1,a.p2-b.p1)<EPS) return true;
                    		if(dot(a.p1-b.p2,a.p2-b.p2)<EPS) return true;
                    		return false;
                    	}
                      else return ( cross(a.p2-a.p1, b.p1-a.p1) * cross(a.p2-a.p1, b.p2-a.p1) < EPS ) && ( cross(b.p2-b.p1, a.p1-b.p1) * cross(b.p2-b.p1, a.p2-b.p1) < EPS );
                    }
                     
                    double segment_dis(Segment a,Segment b){
                    	if(is_intersected_ls(a,b))return 0;
                    	double r=distance_ls_p(a.p1, a.p2, b.p1);
                    	r=min(r,distance_ls_p(a.p1, a.p2, b.p2));
                    	r=min(r,distance_ls_p(b.p1, b.p2, a.p2));
                    	r=min(r,distance_ls_p(b.p1, b.p2, a.p1));
                    	return r;
                    }
                    Point intersection_ls(Segment a, Segment b) {
                      Point ba = b.p2-b.p1;
                      double d1 = abs(cross(ba, a.p1-b.p1));
                      double d2 = abs(cross(ba, a.p2-b.p1));
                      double t = d1 / (d1 + d2);
                     
                      return a.p1 + (a.p2-a.p1) * t;
                    }
                     
                                    string itos( int i ) {
                                    ostringstream s ;
                                    s << i ;
                                    return s.str() ;
                                    }
                                     
                                    int gcd(int v,int b){
                                    	if(v==0) return b;
                                    	if(v>b) return gcd(b,v);
                                    	if(v==b) return b;
                                    	if(b%v==0) return v;
                                    	return gcd(v,b%v);
                                    }
                     
                                    double distans(double x1,double y1,double x2,double y2){
                                    	double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
                                    	return sqrt(rr);
                                    	
                                    }
                                                        /*
        double bekid(double w,int r){
        	if(r==0) return 1.0;
        	if(r==1) return w;
        	if(r%2) return bekid(w,r-1)*w;
        	double f=bekid(w,r/2);
        	return f*f;
        }*/
                                    int mod;
                    int beki(int wa,int rr,int warukazu){
                    	if(rr==0) return 1%warukazu;
                    	if(rr==1) return wa%warukazu;
                    	if(rr%2==1) return (beki(wa,rr-1,warukazu)*wa)%warukazu;
                    	int zx=beki(wa,rr/2,warukazu);
                    	return (zx*zx)%warukazu;
                    }
                          /*          
                    int pr[401000];
                    int inv[401000];
                   
                   

                  
        			int comb(int nn,int rr){
        				int r=pr[nn]*inv[rr];
        				r%=mod;
        				r*=inv[nn-rr];
        				r%=mod;
        				
        				return r;
        			}
                  
                    void gya(int ert){
                    	pr[0]=1;
                    	for(int i=1;i<ert;i++){
                    		pr[i]=(pr[i-1]*i)%mod;
                    	}
                    	for(int i=0;i<ert;i++) inv[i]=beki(pr[i],mod-2,mod);
                    	
                    }
                    */
                    
                  //   cin.tie(0);
        		//	ios::sync_with_stdio(false);
        			//priority_queue<pa3,vector<pa3>,greater<pa3>> pq;            
                     //sort(ve.begin(),ve.end(),greater<int>());


///////////////////////////////////////////////////////////


struct edge{
	int to,cap,num;
};
vector<edge> ZANYO[100020];
int label[100020];
queue<pa> qu_bfs;
int dokomade[100020];
void add_edge_dinic(int s_point,int t_point, int capa){// (s!=t)  s-->t
	
		ZANYO[s_point].pb((edge){t_point,capa,(int)ZANYO[t_point].size()});
		ZANYO[t_point].pb((edge){s_point,0,(int)ZANYO[s_point].size()-1});
}

void bfs_dinic(int s_point,int N){
	for(int i=0;i<N;i++)label[i]=-1;
	while(qu_bfs.size())qu_bfs.pop();
	qu_bfs.push(mp(s_point,0));
	while(qu_bfs.size()){
		pa z=qu_bfs.front();
		qu_bfs.pop();
		if(label[z.first]>=0)continue;
		label[z.first]=z.second;
		for(auto &v:ZANYO[z.first]){
			if(v.cap==0) continue;
			if(v.cap<0){
				cout<<"error"<<endl;
				exit(0);
			}
			if(label[v.to]>=0) continue;
			
			qu_bfs.push(mp(v.to,z.second+1));
		}
	}
	return;
}

int dfs_dinic(int s_point,int t_point, int ima_flow){
	if(s_point==t_point) return ima_flow;
	while(1){
		if(dokomade[s_point]>=ZANYO[s_point].size()) break;
		int edanum=dokomade[s_point];
		if(ZANYO[s_point][edanum].cap<0){
			cout<<"minus"<<endl;
			exit(0);
		}
		if(ZANYO[s_point][edanum].cap<=0 || label[s_point]+1!=label[ZANYO[s_point][edanum].to] ){
			dokomade[s_point]++;
			continue;
		}
		int W=dfs_dinic(ZANYO[s_point][edanum].to,t_point,min(ZANYO[s_point][edanum].cap,ima_flow));
		if(W>0){
			ZANYO[s_point][edanum].cap-=W;
			ZANYO[ZANYO[s_point][edanum].to][ZANYO[s_point][edanum].num].cap+=W;
			return W;
		}
		dokomade[s_point]++;
	}
	return 0;
}
int cnt=0;
int max_flow_dinic(int s_point,int t_point,int N){// Nは頂点数:存在する頂点番号が[0,N) (Nは多めにしてOK)
	int jougen=inf*1000000000ll; //容量の最大値
	int ans_flow=0;
	while(1){
	
		bfs_dinic(s_point,N);
		if(label[t_point]==-1) break;
		for(int i=0;i<N;i++)dokomade[i]=0;
		while(1){
			int ima_flow=dfs_dinic(s_point,t_point,jougen+1); 
			if(ima_flow==0)break;
			ans_flow+=ima_flow;
		}
	}
	return ans_flow;
}

string s[101];
  signed main(){
 	              cin.tie(0);
   		ios::sync_with_stdio(false);
int h,w;
  	cin>>h>>w;
  	for(int i=0;i<h;i++){
  		cin>>s[i];
  		for(int j=0;j<w;j++){
  			if(s[i][j]=='o'){
  				add_edge_dinic(i,j+h,1);
  				add_edge_dinic(j+h,i,1);
  			}
  			if(s[i][j]=='S'){
  				add_edge_dinic(h+w,i,inf);
  				add_edge_dinic(h+w,j+h,inf);
  			}
  			
  			if(s[i][j]=='T'){
  				add_edge_dinic(i,h+w+1,inf);
  				add_edge_dinic(j+h,h+w+1,inf);
  			}
  		}
  	}
  	int g=max_flow_dinic(h+w,h+w+1,h+w+2);
  	if(g>=inf) cout<<-1<<endl;
  	else cout<<g<<endl;
  
  	return 0;
  	
               }
                
                
                




Measured memory_bytes: 3968