#include <bits/stdc++.h>

using namespace std;

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PI;

int dx[4] = { 1, 0, -1, 0 }, dy[4] = { 0, 1, 0, -1 };

int main() {
	int h, w;
	cin >> h >> w;
	char s[50][50];
	int dist[50][50] = {};
	int cnt = 0;
	for (int j = 0; j < h; j++)
		for (int i = 0; i < w; i++) {
			cin >> s[i][j];
			if (s[i][j] == '.')
				cnt++;
			dist[i][j] = 100;
		}
	queue<PI> q;
	q.push({ 0, 0 });
	dist[0][0] = 1;
	while (!q.empty()) {
		PI t = q.front(); q.pop();
		for (int i = 0; i < 4; i++) {
			int ny = t.first + dy[i];
			int nx = t.second + dx[i];
			if (ny < w && ny >= 0 && nx < h && nx >= 0) {
				if (s[ny][nx] == '.')
					if (dist[t.first][t.second] + 1 < dist[ny][nx]) {
						dist[ny][nx] = dist[t.first][t.second] + 1;
						q.push({ ny, nx });
					}
			}
		}
	}
	if (dist[w - 1][h - 1] == 100)
		cout << -1 << endl;
	else
		cout << cnt - dist[w - 1][h - 1] << endl;
	return 0;
}