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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)


import java.io.*;
import java.math.*;
import java.util.*;
import java.util.Map.Entry;

import static java.util.Arrays.*;

public class Main {
	private static final int mod = (int)1e9+7;

	final Random random = new Random(0);
	final IOFast io = new IOFast();

	/// MAIN CODE
	public void run() throws IOException {
		int TEST_CASE = 1;
		while(TEST_CASE-- != 0) {
			h = io.nextInt();
			w = io.nextInt();
			mp = new char[h][];
			for (int i = 0; i < h; i++) mp[i] = io.next();
			for (int y = 0; y < h; y++) {
				for (int x = 0; x < w; x++) if (mp[y][x] == 'S') {
					for (int x2 = 0; x2 < w; x2++) if (mp[y][x2] == 'T') {
						io.out.println(-1);
						return;
					}
					for (int y2 = 0; y2 < h; y2++) if (mp[y2][x] == 'T') {
						io.out.println(-1);
						return;
					}
				}
			}

			int S = w + h, T = S + 1;
			Dinic flow = new Dinic(T + 1);
			for (int y = 0; y < h; y++) {
				for (int x = 0; x < w; x++) if (mp[y][x] != '.') {
					if (mp[y][x] == 'S') { flow.AddEdge(S, x, 1<<29); flow.AddEdge(S, y+w, 1<<29); }
					else if (mp[y][x] == 'T') { flow.AddEdge(x, T, 1<<29); flow.AddEdge(y+w, T, 1<<29); }
					else { flow.AddEdge(y+w, x, 1); flow.AddEdge(x, y+w, 1); }
				}
			}
			io.out.println(flow.MaxFlow(S, T));
		}
	}
	
	static class Dinic {
		final int INF = 1 << 29;

//		List<List<Edge>> G;
		AdjListGraph g;
		int[] level, iter, q;
		List<int[]> es = new ArrayList<>();

		void bfs(int s) {
			for (int i = 0; i < level.length; i++) level[i] = -1;
//			Queue<Integer> q = new LinkedList<Integer>();
			int qs = 0, qt = 0;
			level[s] = 0;
			q[qt++] =s;
			while (qs != qt) {
				int v = q[qs++];
				for(int e = g.head[v]; e != -1; e = g.next[e]) {
					final int t = g.to[e];
					if (g.cap[e] > 0 && level[t] < 0) {
						level[t] = level[v] + 1;
						q[qt++] = t;
					}
				}
			}
		}

		int dfs(int v, int t, int f) {
			if (v == t) return f;
			for (int i = iter[v]; i != -1; i = iter[v] = g.next[i]) {
				if (g.cap[i] > 0 && level[v] < level[g.to[i]]) {
					int d = dfs(g.to[i], t, Math.min(f, g.cap[i]));
					if (d > 0) {
						g.cap[i] -= d;
						g.cap[g.rev[i]] += d;
						return d;
					}
				}
			}
			return 0;
		}

		public void AddEdge(int from, int to, int cap) {
			es.add(new int[]{from, to, cap, });
//			g.addEdge(from, to, cap, g.m + 1);
//			g.addEdge(to, from, 0, g.m - 1);
		}
		
		private void build() {
			if(g == null) {
				g = new AdjListGraph(level.length, 2 * es.size() * 2);
				for(int[] e : es) {
					g.addEdge(e[0], e[1], e[2], g.m + 1);
					g.addEdge(e[1], e[0], 0, g.m - 1);
				}
			}
		}

		public int MaxFlow(int s, int t) {
			build();
			int flow = 0;
			for (; ; ) {
				bfs(s);
				if (level[t] < 0) return flow;
				for (int i = 0; i < iter.length; i++) iter[i] = g.head[i];
				for (int f = 0; (f = dfs(s, t, INF)) > 0; )
					flow += f;
			}
		}

		public int BipartiteMatching(int s, int t) {
			return MaxFlow(s, t);
		}
		
		void clear() {
			g.clear();
		}
		
		void clear(int n) {
			g.clear(n);
		}

		public Dinic(int size) {
			level = new int[size];
			iter = new int[size];
			q = new int[size];
		}

		int[][] generateGraphCut(int S, int T) {
			final int n = g.head.length;
			int[] q = new int[n];
			final boolean[] used = new boolean[n];
			used[S] = true;
			
			int cnt = 0;
			int s = 0, t = 0;
			q[t++] = S;
			while(s != t) {
				final int v = q[s++];
				cnt++;
				for(int u = g.head[v]; u != -1; u = g.next[u]) {
					final int to = g.to[u];
					final int cap = g.cap[u];
					if(cap != 0 && !used[to]) {
						q[t++] = to;
						used[to] = true;
					}
				}
			}
			final int[][] res = new int[2][];
			final int[] len = new int[2];
			res[0] = new int[cnt];
			res[1] = new int[n - cnt];
			for(int i = 0; i < n; i++) {
				final int x = used[i] ? 0 : 1;
				res[x][len[x]++] = i;
			}
			return res;
		}
		
		static class AdjListGraph {
			int m;
			int[] head, next, to, rev;
			int[] cap;

			public AdjListGraph(int V, int E) {
				head = new int[V];
				next = new int[E];
				to = new int[E];
				cap = new int[E];
				rev = new int[E];
				clear();
			}

			public void clear(int v) {
				m = 0;
				for(int i = 0; i < v; i++) {
					head[i] = -1;
				}
			}

			public void clear() {
				m = 0;
				Arrays.fill(head, -1);
			}

			public void addEdge(int s, int t, int c, int r) {
				next[m] = head[s];
				head[s] = m;
				to[m] = t;
				cap[m] = c;
				rev[m++] = r;
			}
		}
	}

	
	int w, h;
	char[][] mp;
	
	int gen() {
		final int LEAF = -4;
		final int LINE = -1;
		final int NONE = -2;
		final int INVALID = -3;
		int[][] mp2 = new int[2*h+1][2*w+1];
		int[][] mp3 = new int[2*h+1][2*w+1];
		for (int[] m : mp2) Arrays.fill(m, NONE);
		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) if (mp[y][x] != '.') {
				mp2[2*y+1][2*x+1] = LEAF;
				mp3[2*y+1][2*x+1] = LEAF;
			}
		}
		for (int y = 0; y < mp2.length; y++) {
			for (int x = 0; x < mp2[y].length; x++) if (mp2[y][x] == LEAF) {
				for (int x2 = x+1; x2 < mp2[y].length; x2++) if (mp2[y][x2] == LEAF) {
					for (int x3 = x+1; x3 < x2; x3++) mp2[y][x3] = LINE;
					break;
				}
				for (int y2 = y+1; y2 < mp2.length; y2++) if (mp2[y2][x] == LEAF) {
					for (int y3 = y+1; y3 < y2; y3++) mp2[y3][x] = LINE;
					break;
				}
			}
		}
		for (int y = 0; y < mp2.length; y++) {
			for (int x = 0; x < mp2[y].length; x++) if (mp2[y][x] == LEAF) {
				mp2[y][x] = LINE;
			}
		}

		mp2[0][0] = mp2[mp2.length - 1][mp2[0].length - 1] = INVALID;

		final Comparator<int[]> cmp = new Comparator<int[]>() {
			
			@Override
			public int compare(int[] arg0, int[] arg1) {
				if (arg0[0] != arg1[0]) return arg0[0] - arg1[0];
				return arg0[1] - arg1[1];
			}
		};
		List<TreeSet<int[]>> g = new ArrayList<>();

		int S = 0, T = 1;
		int v = 0;
		
		int[] dxy = new int[]{1,0,-1,0,1};
		int[] q = new int[w*h*10+100];
		for (int y = 0; y < mp2.length; y++) {
			for (int x = 0; x < mp2[y].length; x++) if (mp2[y][x] == NONE) {
				int s = 0, t = 0;
				q[t++] = y<<16|x;
				mp2[y][x] = v;
				while (s != t) {
					int xx = q[s]&0xFFFF;
					int yy = q[s]>>16;
					s++;
					for (int d = 0; d < 4; d++) {
						int x2 = xx + dxy[d];
						int y2 = yy + dxy[d+1];
						if (x2 < 0 || x2 >= mp2[y].length || y2 < 0 || y2 >= mp2.length) continue;
						if (mp2[y2][x2] != NONE) continue;
						mp2[y2][x2] = v;
						q[t++] = y2<<16|x2;
					}
//					dump(x, y, xx, yy);
				}
				v++;
				g.add(new TreeSet<>(cmp));
			}
		}
		if (v == 1) return 0;
		for (int y = 0; y < mp2.length; y++) {
			dump(mp2[y]);
		}
		for (int y = 0; y < mp2.length; y++) {
			for (int x = 0; x < mp2[y].length; x++) if (mp2[y][x] == LINE) {
				for (int d = 0; d < 4; d++) {
					int x1 = x - dxy[d];
					int y1 = y - dxy[d+1];
					int x2 = x + dxy[d];
					int y2 = y + dxy[d+1];
					if (mp2[y2][x2] == LINE || mp2[y1][x1] == LINE) continue;
					if (mp2[y2][x2] == mp2[y1][x1]) continue;
					int w1 = 0, w2 = 0;
					for (int x3 = x, y3 = y; ; x3 += dxy[d+1], y3 += dxy[d]) {
						if (x3 < 0 || x3 >= mp2[y].length || y3 < 0 || y3 >= mp2.length) break;
						if (mp3[y3][x3] == LEAF) w1++;
						if (x3 == 1 && y3 == 1 || x3 == mp2[0].length - 2 || y3 == mp2.length) w1 = 1<<29;
					}
					for (int x3 = x, y3 = y; ; x3 -= dxy[d+1], y3 -= dxy[d]) {
						if (x3 < 0 || x3 >= mp2[y].length || y3 < 0 || y3 >= mp2.length) break;
						if (mp3[y3][x3] == LEAF) w2++;
						if (x3 == 1 && y3 == 1 || x3 == mp2[0].length - 2 || y3 == mp2.length) w2 = 1<<29;
					}
					int v1 = mp2[y2][x2];
					int v2 = mp2[y1][x1];
					g.get(v1).add(new int[]{v2,Math.min(w1, w2)});
					g.get(v2).add(new int[]{v1,Math.min(w1, w2)});
//					dump(x, y, v1, v2);
				}
			}
		}
		
		int[] dist = new int[v];
		Arrays.fill(dist, Integer.MAX_VALUE);
		dist[S] = 0;
		PriorityQueue<Long> que = new PriorityQueue<>();
		que.add(0L<<32|S);
		while (!que.isEmpty()) {
			long val = que.poll();
			int cur = (int)(val&0xFFFFFFFFL);
			if (dist[cur] != val>>>32) continue;
			for (int[] e : g.get(cur)) if (dist[e[0]] > dist[cur] + e[1]) {
				dist[e[0]] = dist[cur] + e[1];
				que.add((long)dist[e[0]]<<32|e[0]);
			}
		}
		
		return dist[T];
	}
	
	/// TEMPLATE
	static int gcd(int n, int r) { return r == 0 ? n : gcd(r, n%r); }
	static long gcd(long n, long r) { return r == 0 ? n : gcd(r, n%r); }
	
	static <T> void swap(T[] x, int i, int j) { T t = x[i]; x[i] = x[j]; x[j] = t; }
	static void swap(int[] x, int i, int j) { int t = x[i]; x[i] = x[j]; x[j] = t; }

	void printArrayLn(int[] xs) { for(int i = 0; i < xs.length; i++) io.out.print(xs[i] + (i==xs.length-1?"\n":" ")); }
	void printArrayLn(long[] xs) { for(int i = 0; i < xs.length; i++) io.out.print(xs[i] + (i==xs.length-1?"\n":" ")); }
	
	static void dump(Object... o) { System.err.println(Arrays.deepToString(o)); } 
	
	void main() throws IOException {
		//		IOFast.setFileIO("rle-size.in", "rle-size.out");
		try { run(); }
		catch (EndOfFileRuntimeException e) { }
		io.out.flush();
	}
	public static void main(String[] args) throws IOException { new Main().main(); }
	
	static class EndOfFileRuntimeException extends RuntimeException {
		private static final long serialVersionUID = -8565341110209207657L; }

	static
	public class IOFast {
		private BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		private PrintWriter out = new PrintWriter(System.out);

		void setFileIn(String ins) throws IOException { in.close(); in = new BufferedReader(new FileReader(ins)); }
		void setFileOut(String outs) throws IOException { out.flush(); out.close(); out = new PrintWriter(new FileWriter(outs)); }
		void setFileIO(String ins, String outs) throws IOException { setFileIn(ins); setFileOut(outs); }

		private static int pos, readLen;
		private static final char[] buffer = new char[1024 * 8];
		private static char[] str = new char[500*8*2];
		private static boolean[] isDigit = new boolean[256];
		private static boolean[] isSpace = new boolean[256];
		private static boolean[] isLineSep = new boolean[256];

		static { for(int i = 0; i < 10; i++) { isDigit['0' + i] = true; } isDigit['-'] = true; isSpace[' '] = isSpace['\r'] = isSpace['\n'] = isSpace['\t'] = true; isLineSep['\r'] = isLineSep['\n'] = true; }
		public int read() throws IOException { if(pos >= readLen) { pos = 0; readLen = in.read(buffer); if(readLen <= 0) { throw new EndOfFileRuntimeException(); } } return buffer[pos++]; }
		public int nextInt() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isSpace); int i = 0; int ret = 0; if(str[0] == '-') { i = 1; } for(; i < len; i++) ret = ret * 10 + str[i] - '0'; if(str[0] == '-') { ret = -ret; } return ret; }
		public long nextLong() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isSpace); int i = 0; long ret = 0; if(str[0] == '-') { i = 1; } for(; i < len; i++) ret = ret * 10 + str[i] - '0'; if(str[0] == '-') { ret = -ret; } return ret; }
		public char nextChar() throws IOException { while(true) { final int c = read(); if(!isSpace[c]) { return (char)c; } } }
		int reads(int len, boolean[] accept) throws IOException { try { while(true) { final int c = read(); if(accept[c]) { break; } if(str.length == len) { char[] rep = new char[str.length * 3 / 2]; System.arraycopy(str, 0, rep, 0, str.length); str = rep; } str[len++] = (char)c; } } catch(EndOfFileRuntimeException e) { ; } return len; }
		int reads(char[] cs, int len, boolean[] accept) throws IOException { try { while(true) { final int c = read(); if(accept[c]) { break; } cs[len++] = (char)c; } } catch(EndOfFileRuntimeException e) { ; } return len; }
		public char[] nextLine() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isLineSep); try { if(str[len-1] == '\r') { len--; read(); } } catch(EndOfFileRuntimeException e) { ; } return Arrays.copyOf(str, len); }
		public String nextString() throws IOException { return new String(next()); }
		public char[] next() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isSpace); return Arrays.copyOf(str, len); }
//		public int next(char[] cs) throws IOException { int len = 0; cs[len++] = nextChar(); len = reads(cs, len, isSpace); return len; }
		public double nextDouble() throws IOException { return Double.parseDouble(nextString()); }
		public long[] nextLongArray(final int n) throws IOException { final long[] res = new long[n]; for(int i = 0; i < n; i++) { res[i] = nextLong(); } return res; }
		public int[] nextIntArray(final int n) throws IOException { final int[] res = new int[n]; for(int i = 0; i < n; i++) { res[i] = nextInt(); } return res; }
		public int[][] nextIntArray2D(final int n, final int k) throws IOException { final int[][] res = new int[n][]; for(int i = 0; i < n; i++) { res[i] = nextIntArray(k); } return res; }
		public int[][] nextIntArray2DWithIndex(final int n, final int k) throws IOException { final int[][] res = new int[n][k+1]; for(int i = 0; i < n; i++) { for(int j = 0; j < k; j++) { res[i][j] = nextInt(); } res[i][k] = i; } return res; }
		public double[] nextDoubleArray(final int n) throws IOException { final double[] res = new double[n]; for(int i = 0; i < n; i++) { res[i] = nextDouble(); } return res; }
	}
}