// Arup Guha
// 3/24/2015
// Solution to February 14 Bronze USACO Problem: Mirror

import java.util.*;
import java.io.*;

public class mirror {

	public static void main(String[] args) throws Exception {

		// Read in the grid.
		BufferedReader stdin = new BufferedReader(new FileReader("mirror.in"));
		StringTokenizer tok = new StringTokenizer(stdin.readLine());
		int rows = Integer.parseInt(tok.nextToken());
		int cols = Integer.parseInt(tok.nextToken());
		String[] grid = new String[rows];
		for (int i=0; i<rows; i++)
			grid[i] = stdin.readLine();
		stdin.close();

		// Try horizontal shots.
		int result = 1;
		for (int i=0; i<rows; i++) {
			result = Math.max(result, sim(grid, i, -1, 0, 1));
			result = Math.max(result, sim(grid, i, cols, 0, -1));
		}

		// Try vertical shots.
		for (int i=0; i<cols; i++) {
			result = Math.max(result, sim(grid, -1, i, 1, 0));
			result = Math.max(result, sim(grid, rows, i, -1, 0));
		}

		// Write out the result.
		BufferedWriter fout = new BufferedWriter(new FileWriter("mirror.out"));
		fout.write(result+"\n");
		fout.close();
	}

	// Note: +x is going down...
	public static int sim(String[] grid, int x, int y, int dX, int dY) {

		int cnt = 0;

		while (true) {

			// Move the laser beam.
			cnt++;
			x += dX;
			y += dY;

			// Get out!
			if (x<0 || y<0 || x>=grid.length || y>=grid[0].length()) break;

			// This is roughly what happens.
			int newdX = dY;
			int newdY = dX;

			// For this mirror, we switch signs.
			if (grid[x].charAt(y) == '/') {
				newdX = -newdX;
				newdY = -newdY;
			}

			// Now, update direction.
			dX = newdX;
			dY = newdY;
		}

		// Our result.
		return cnt-1;
	}
}