插头DP模板

/*
插头dp模板
抄的GNAQ 的
括号表示法

*/
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<iostream>
#include<queue>
#include<cmath>
#define ll long long
#define M 13
#define mmp make_pair
using namespace std;
int read() {
	int nm = 0, f = 1;
	char c = getchar();
	for(; !isdigit(c); c = getchar()) if(c == '-') f = -1;
	for(; isdigit(c); c = getchar()) nm = nm * 10 + c - '0';
	return nm * f;
}
const int hs = 299987;
int mp[M][M], ex, ey, now, last, bit[30], g[2][300010], tot[2], n, m;
ll ans, f[2][300010];

struct Note {
	int nxt, to;
} note[300010];
int head[300010], cnt = 0;

char s[M];

void insert(int x, ll v) {
	int key = x % hs;
	for(int i = head[key]; i; i = note[i].nxt) {
		if(g[now][note[i].to] == x) {
			f[now][note[i].to] += v;
			return;
		}
	}
	tot[now]++;
	g[now][tot[now]] = x;
	f[now][tot[now]] = v;

	note[++cnt].nxt = head[key];
	head[key] = cnt;
	note[cnt].to = tot[now];
}

void Dp() {
	now = 1, last = 0;
	tot[now] = 1;
	f[now][1] = 1;
	g[now][1] = 0;
	for(int i = 1; i <= n; i++) {
		for(int j = 1; j <= tot[now]; j++) g[now][j] <<= 2;
		for(int j = 1; j <= m; j++) {
			cnt = 0;
			memset(head, 0, sizeof(head));
			swap(now, last);
			tot[now] = 0;
			ll nowans;
			int nowsta, sd, sr;
			for(int k = 1; k <= tot[last]; k++) {
				nowsta = g[last][k], nowans = f[last][k];
				sd = (nowsta >> bit[j]) % 4, sr = (nowsta >> bit[j - 1]) % 4;
				if(!mp[i][j]) {
					if(!sd && !sr) insert(nowsta, nowans);
				} else if(!sd && !sr) {
					if(mp[i + 1][j] && mp[i][j + 1]) insert(nowsta + (1 << bit[j - 1]) + 2 * (1 << bit[j]), nowans);
				} else if(!sd && sr) {
					if(mp[i + 1][j]) insert(nowsta, nowans);
					if(mp[i][j + 1]) insert(nowsta - sr * (1 << bit[j - 1]) + sr * (1 << bit[j]), nowans);
				} else if(sd && !sr) {
					if(mp[i + 1][j]) insert(nowsta - sd * (1 << bit[j]) + sd * (1 << bit[j - 1]), nowans);
					if(mp[i][j + 1]) insert(nowsta, nowans);
				} else if(sd == 1 && sr == 1) {
					int count = 1;
					for(int l = j + 1; l <= m; l++) {
						if((nowsta >> bit[l]) % 4 == 1) count++;
						else if((nowsta >> bit[l]) % 4 == 2) count--;
						if(!count) {
							insert(nowsta - (1 << bit[l]) - (1 << bit[j]) - (1 << bit[j - 1]), nowans);
							break;
						}
					}
				} else if(sd == 2 && sr == 2) {
					int count = 1;
					for(int l = j - 2; l >= 0; l--) {
						if((nowsta >> bit[l]) % 4 == 1) count--;
						else if((nowsta >> bit[l]) % 4 == 2) count++;
						if(!count) {
							insert(nowsta - 2 * (1 << bit[j]) - 2 * (1 << bit[j - 1]) + (1 << bit[l]), nowans);
							break;
						}
					}
				} else if(sd == 1 && sr == 2) {
					insert(nowsta - 2 * (1 << bit[j - 1]) - (1 << bit[j]), nowans);
				} else if(sd == 2 && sr == 1) {
					if(i == ex && j == ey) ans += nowans;
				}
			}
		}
	}
}

int main() {
	n = read(), m = read();
	for(int i = 1; i <= n; i++) {
		scanf("%s", s + 1);
		for(int j = 1; j <= m; j++) {
			if(s[j] == '.') mp[i][j] = 1, ex = i, ey = j;
		}
	}
	for(int i = 1; i <= 25; i++) bit[i] = i << 1;
	Dp();
	cout << ans << '\n';
	return 0;
}