名副其实的广搜题， 但是我仍然不会 废话不多说，直接上代码

#include <iostream>
#include <queue>
using namespace std;
int r, c, x, y;
int dir[8][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1}, {-1, -1}, {1, -1}, {-1, 1}, {1, 1}};
char ma[105][105];
bool vis[105][105];
int ans = 0;
struct node{
	int x, y, s;
};
queue<node > q;
void bfs(int x, int y){
	vis[x][y] = 1;
	q.push((node){x, y, 0});
	while(!q.empty()){
		node p = q.front();
		q.pop();
		ans = max(ans, p.s);
		for(int i=0; i<8; i++){
			int nx = p.x + dir[i][0];
			int ny = p.y + dir[i][1];
			if(1 <= nx && nx <= r && 1 <= ny && ny <= c){
				if(vis[nx][ny] == 0 && ma[nx][ny] != '*'){
					vis[nx][ny] = 1;
					q.push((node){nx, ny, p.s + 1});
				}
			}
		}
	}
}
int main(){
	cin>>c>>r>>x>>y;
	for(int i=1; i<=r; i++){
		for(int j=1; j<=c; j++){
			cin>>ma[i][j];
		}
	}
	bfs(r - y + 1, x);
	cout<<ans<<endl;
}