#include<iostream>
#include<cstring>
#include<queue>
#include<algorithm>
#define x first
#define y second

using namespace std;

typedef pair<int,int> PII;
int n,m;
PII start;
const int N = 110;
char g[N][N];
int dis[N][N];
int res = -10;

int bfs(){
    queue<PII> q;
    memset(dis,-1,sizeof dis);
    q.push(start);
    dis[start.x][start.y] = 0;   //赋初值!,否则从-1 加起
    while(q.size()){
        auto t = q.front();
        q.pop();               //不要忘记弹出,否则死循环
        for(int i = - 1; i <= 1; i ++)   //八个方向,不用开方向数组
            for(int j = -1; j <= 1; j ++){
                int a = t.x + i,b = t.y + j;
                if(a < 1 || a > n || b < 1 || b > m) continue;  //注意修改 不是a < 0 ..
                if(dis[a][b] != -1) continue;
                if(g[a][b] == '*') continue;
                dis[a][b] = dis[t.x][t.y] + 1;
                res = max(res,dis[a][b]); //求解该题关键点,就是到达最后一块草地的距离就是答案
                q.push({a,b});
            }
    }
    return res;
}
int main(){
    cin >> m >> n >> start.y >> start.x;  //输入x1,y1是数学坐标系
    start.x = n - start.x + 1;  //修改得到代码坐标系,输出x2,y2,即y2 = x1, x2 = n - y1 + 1  
    for(int i = 1 ; i <= n ; i ++)  //注意输入 横纵坐标从1开始！
        cin  >> (g[i] + 1);
    cout << bfs() << endl;
    return 0;
}