Problem:
Score : 800 points

Problem Statement

There is a pond with a rectangular shape.
The pond is divided into a grid with H rows and W columns of squares.
We will denote the square at the i-th row from the top and j-th column from the left by (i,\ j).

Some of the squares in the pond contains a lotus leaf floating on the water.
On one of those leaves, S, there is a frog trying to get to another leaf T.
The state of square (i,\ j) is given to you by a character a_{ij}, as follows:

. : A square without a leaf.

o : A square with a leaf floating on the water.

S : A square with the leaf S.

T : A square with the leaf T.

The frog will repeatedly perform the following action to get to the leaf T: "jump to a leaf that is in the same row or the same column as the leaf where the frog is currently located."

Snuke is trying to remove some of the leaves, other than S and T, so that the frog cannot get to the leaf T.
Determine whether this objective is achievable. If it is achievable, find the minimum necessary number of leaves to remove.

Constraints

2 ≤ H, W ≤ 100

a_{ij} is ., o, S or T.

There is exactly one S among a_{ij}.

There is exactly one T among a_{ij}.

Input

Input is given from Standard Input in the following format:

H W
a_{11} ... a_{1W}
:
a_{H1} ... a_{HW}

Output

If the objective is achievable, print the minimum necessary number of leaves to remove.
Otherwise, print -1 instead.

Sample Input 1

3 3
S.o
.o.
o.T

Sample Output 1

2

Remove the upper-right and lower-left leaves.

Sample Input 2

3 4
S...
.oo.
...T

Sample Output 2

0

Sample Input 3

4 3
.S.
.o.
.o.
.T.

Sample Output 3

-1

Sample Input 4

10 10
.o...o..o.
....o.....
....oo.oo.
..oooo..o.
....oo....
..o..o....
o..o....So
o....T....
....o.....
........oo

Sample Output 4

5

Solution in Rust (1.15.1) (judge verdict: Accepted)

#![allow(unused_imports)]
#![allow(non_snake_case, unused)]

use std::cmp::*;
use std::collections::*;
use std::ops::*;

// https://atcoder.jp/contests/hokudai-hitachi2019-1/submissions/10518254

macro_rules! eprint {
	($($t:tt)*) => {{
		use ::std::io::Write;
		let _ = write!(::std::io::stderr(), $($t)*);
	}};
}
macro_rules! eprintln {
	() => { eprintln!(""); };
	($($t:tt)*) => {{
		use ::std::io::Write;
		let _ = writeln!(::std::io::stderr(), $($t)*);
	}};
}
macro_rules! dbg {
	($v:expr) => {{
		let val = $v;
		eprintln!("[{}:{}] {} = {:?}", file!(), line!(), stringify!($v), val);
		val
	}}
}

macro_rules! mat {
	($($e:expr),*) => { Vec::from(vec![$($e),*]) };
	($($e:expr,)*) => { Vec::from(vec![$($e),*]) };
	($e:expr; $d:expr) => { Vec::from(vec![$e; $d]) };
	($e:expr; $d:expr $(; $ds:expr)+) => { Vec::from(vec![mat![$e $(; $ds)*]; $d]) };
}

macro_rules! ok {
	($a:ident$([$i:expr])*.$f:ident()$(@$t:ident)*) => {
		$a$([$i])*.$f($($t),*)
	};
	($a:ident$([$i:expr])*.$f:ident($e:expr$(,$es:expr)*)$(@$t:ident)*) => { {
		let t = $e;
		ok!($a$([$i])*.$f($($es),*)$(@$t)*@t)
	} };
}

pub fn readln() -> String {
	let mut line = String::new();
	::std::io::stdin().read_line(&mut line).unwrap_or_else(|e| panic!("{}", e));
	line
}

macro_rules! read {
	($($t:tt),*; $n:expr) => {{
		let stdin = ::std::io::stdin();
		let ret = ::std::io::BufRead::lines(stdin.lock()).take($n).map(|line| {
			let line = line.unwrap();
			let mut it = line.split_whitespace();
			_read!(it; $($t),*)
		}).collect::<Vec<_>>();
		ret
	}};
	($($t:tt),*) => {{
		let line = readln();
		let mut it = line.split_whitespace();
		_read!(it; $($t),*)
	}};
}

macro_rules! _read {
	($it:ident; [char]) => {
		_read!($it; String).chars().collect::<Vec<_>>()
	};
	($it:ident; [u8]) => {
		Vec::from(_read!($it; String).into_bytes())
	};
	($it:ident; usize1) => {
		$it.next().unwrap_or_else(|| panic!("input mismatch")).parse::<usize>().unwrap_or_else(|e| panic!("{}", e)) - 1
	};
	($it:ident; [usize1]) => {
		$it.map(|s| s.parse::<usize>().unwrap_or_else(|e| panic!("{}", e)) - 1).collect::<Vec<_>>()
	};
	($it:ident; [$t:ty]) => {
		$it.map(|s| s.parse::<$t>().unwrap_or_else(|e| panic!("{}", e))).collect::<Vec<_>>()
	};
	($it:ident; $t:ty) => {
		$it.next().unwrap_or_else(|| panic!("input mismatch")).parse::<$t>().unwrap_or_else(|e| panic!("{}", e))
	};
	($it:ident; $($t:tt),+) => {
		($(_read!($it; $t)),*)
	};
}


pub fn main() {
	let _ = ::std::thread::Builder::new().name("run".to_string()).stack_size(32 * 1024 * 1024).spawn(run).unwrap().join();
}

const MOD: u32 = 1_000_000_007;
const INF: i64 = std::i64::MAX/3;

#[derive(Copy,Clone)]
struct Edge {
	to: usize,
	cap: i64,
	rev: usize,
}

struct Dinic {
	edge: Vec<Vec<Edge>>,
	level: Vec<i64>,
	iter: Vec<usize>,
	n: usize,
}

impl Dinic {
	pub fn new(n: usize) -> Self {
		Dinic {
			edge: vec![vec![];n],
			level: vec![-1;n],
			iter: vec![0;n],
			n: n,
		}
	}

	pub fn add_edge(&mut self, s: usize, t: usize, c: i64) {
		let mut tmp = self.edge[t].len();
		self.edge[s].push(Edge{to: t, cap: c, rev: tmp});
		let mut tmp = self.edge[s].len();
		self.edge[t].push(Edge{to: s, cap: 0, rev: tmp-1});
	}

	pub fn add_multi_edge(&mut self, s: usize, t: usize, c: i64) {
		let mut tmp = self.edge[t].len();
		self.edge[s].push(Edge{to: t, cap: c, rev: tmp});
		let mut tmp = self.edge[s].len();
		self.edge[t].push(Edge{to: s, cap: c, rev: tmp-1});
	}

	pub fn bfs(&mut self, s: usize) {
		self.level = vec![-1;self.n];
		self.level[s] = 0;
		let mut q = VecDeque::new();
		q.push_back(s);
		while let Some(cur) = q.pop_front() {
			for &e in &self.edge[cur] {
				if e.cap > 0 && self.level[e.to] < 0 {
					self.level[e.to] = self.level[cur] + 1;
					q.push_back(e.to);
				}
			}
		}
	} 

	pub fn dfs(&mut self, v: usize, t: usize, val: i64) -> i64{
		if v==t {
			return val;
		}
		for i in self.iter[v]..self.edge[v].len() {
			let e = self.edge[v][i];
			if e.cap > 0 && self.level[v] < self.level[e.to] {
				let d = self.dfs(e.to,t,min(val,e.cap));
				if d > 0 {
					self.edge[v][i].cap -= d;
					self.edge[e.to][e.rev].cap += d;
					return d;
				}
			}
			// self.iter[v] += 1;
		}
		return 0;
	}

	pub fn calc(&mut self, s: usize, t: usize) -> i64{
		let mut flow = 0;
		loop {
			self.bfs(s);
			if self.level[t] < 0 {
				return flow;
			}
			self.iter = vec![0;self.n];
			let mut f = 0;
			loop {
				let ret = self.dfs(s,t,INF);
				if ret == 0 {
					break;
				}
				f += ret;
			}
			flow += f;
		}
	}

}

fn solve() {
	let (h,w) = read!(usize,usize);
	let a = read!(String;h);
	let mut board = vec![vec![' ';w];h];
	for i in 0..h {
		for (j,c) in a[i].chars().enumerate() {
			board[i][j] = c;
		}
	}
	let mut s = 0;
	let mut t = 1;
	let mut dinic = Dinic::new(h+w+2);
	let mut count = 0;
	for i in 0..h {
		for j in 0..w {
			if board[i][j]=='S' {
				dinic.add_edge(s, i+2, INF);
				dinic.add_edge(s, h+j+2, INF);
			}
			if board[i][j]=='T' {
				dinic.add_edge(i+2, t, INF);
				dinic.add_edge(h+j+2, t, INF);
			}
			if board[i][j]=='o' {
				dinic.add_multi_edge(i+2, h+j+2, 1);
			}
		}
	}
	let mut val = dinic.calc(s,t);
	if val>=INF {
		println!("-1");
	}
	else{
		println!("{}",val);
	}
}

fn run() {
    solve();
}