#include <bits/stdc++.h>
                            #include<iostream>
                            #include<cstdio>
                            #include<vector>
                            #include<queue>
                            #include<map>
                            #include<cstring>
                            #include<string>
                            #include <math.h>
                            #include<algorithm>
                        //    #include <boost/multiprecision/cpp_int.hpp>
                            #include<functional>
                     #define int long long
                            #define inf  1000000007
                            #define pa pair<int,int>
                            #define ll long long
                            #define pal pair<double,int>
                            #define ppa pair<string,pa>
                            #define ssa pair<string,int>
                            #define  mp make_pair
                            #define  pb push_back
                            #define EPS (1e-10)
                            #define equals(a,b) (fabs((a)-(b))<EPS)
                     
                            using namespace std;
                     //priority_queue<int, vector<int>, greater<int> > que;
                            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;
                     
                            struct Segment{
                            Point p1,p2;
                            };
                     
                        double hen(Vector a){
                        if(fabs(a.x)<EPS && a.y>0) return acos(0);
                        else if(fabs(a.x)<EPS && a.y<0) return 3*acos(0);
                        else if(fabs(a.y)<EPS && a.x<0) return 2*acos(0);
                        else if(fabs(a.y)<EPS && a.x>0) return 0.0;
                        else if(a.y>0) return acos(a.x/a.absv());
                        else return 2*acos(0)+acos(-a.x/a.absv());
                     
                        }
                     
                string itos( int i ) {
                ostringstream s ;
                s << i ;
                return s.str() ;
                }
                 
                int gcd(int v,int 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 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;
                            }
                        
                double distans(double x1,double y1,double x2,double y2){
                	double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
                	return sqrt(rr);
                	
                }

   struct edge{ int to,cap,rev;};
vector<edge> G[100010];
bool used[100010];

void add_edge(int from ,int to, int cap){
 G[from].push_back((edge){to,cap,G[to].size()});
 G[to].push_back((edge){from,0,G[from].size()-1});
}

int ddfs(int v,int t,int f){
if(v==t) return f;
used[v]=true;
for(int i=0;i<G[v].size();i++){
edge &e=G[v][i];
if(!used[e.to] && e.cap>0){
int d=ddfs(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 flow=0;
for(;;){
memset(used,0,sizeof(used));
int f =ddfs(s,t,inf);
if(f==0) return flow;
flow +=f;
}
}
                         //----------------kokomade tenpure------------


 signed  main(){
 	int h,w;
 	cin>>h>>w;
 	
//cin>>n;
 
 	
 	for(int i=0;i<h;i++){
 		string s;
 		cin>>s;
 		for(int j=0;j<s.length();j++){
 			if(s[j]=='.') continue;
 			if(s[j]=='o') {
 				add_edge(i,200+j,1);
 				add_edge(200+j,i,1);
 			}
 			if(s[j]=='S'){
 				add_edge(400,i,100000000);
 				add_edge(400,200+j,100000000);
 			}
 			if(s[j]=='T'){
 				add_edge(i,500,100000000);
 				add_edge(200+j,500,100000000);
 			}
 		}
 	}
 	int ans=max_flow(400,500);
	if(ans>100000) ans=-1;
 	cout<<ans<<endl;
 	
 //	cout<<i<<endl;
 	//  	printf("%.10f\n",ans[n-1]);
                    	return 0;
}

Measured memory_bytes: 3968