#include <iostream>
#include <queue>
#include <cstdio>
using namespace std;
char ch[1005][1005] = {{}};
int bfs(int x, int y){
	int rtn = 1;
	queue<int> q;
	q.push(x << 16 + y);
	while (!q.empty()){
		int a = q.front() >> 16, b = (q.front() << 16) >> 16;
		q.pop();
		int fnd = 0;
		if (!(ch[a-1][b] == 'F'||ch[a+1][b] == 'F'||ch[a][b-1] == 'F'||ch[a][b+1] == 'F'))
			fnd = -1;
		if (ch[a][b] == 'F')
			return -1;
		ch[a][b] = 'F';
		if (ch[a+1][b] == 'O')
			q.push((a + 1) << 16 + b),++fnd,++rtn;
		if (ch[a-1][b] == 'O')
			if (fnd==1)
				return -1;
			else
				q.push((a - 1) << 16 + b),++fnd,++rtn;
		if (ch[a][b+1] == 'O')
			if (fnd==1)
				return -1;
			else
				q.push(a << 16 + b + 1),++fnd,++rtn;
		if (ch[a][b-1] == 'O')
			if (fnd==1)
				return -1;
			else
				q.push(a << 16 + b - 1),++rtn;
	}
	return rtn;
}
int main(){
	int n,m,k;
	unsigned long long ans = 1;
	cin >> n >> m >> k;
	for (int i = 1; i <= n; ++i)
		for (int j = 1; j <= m; ++j)
			scanf(" %c",&ch[i][j]);
	for (int i = 1; i <= n; ++i)
		for (int j = 1; j <= m; ++j)
			if (ch[i][j] == 'O'){
				int rtn = bfs(i,j);
				if (rtn == -1){
					cout << 0;
					return 0;
				}
				ans *= k;
				for (int l = 1; l < rtn; ++l)
					ans *= (k - 1), ans %= 998244353;
			}
	cout << (ans % 998244353);
	return 0;
}

为什么会错