#include<iostream>
#include<algorithm>
#include<cstring>
#include<queue>
#define x first
#define y second
using namespace std;
typedef pair<int,int> PII;
const int N=110;
char g[N][N];
int n,m;
int bx,by,X,Y;
int bfs()
{
    int ans=-0x3f;
    queue<PII> Q;
    Q.push({bx,by});
    int dist[N][N];
    memset(dist,-1,sizeof dist);
    dist[bx][by]=0;
    int dx[8] = {-1, -1, -1, 0, 1, 1, 1, 0};
    int dy[8] = {-1, 0, 1, 1, 1, 0, -1, -1};
    while(!Q.empty())
    {
        PII t=Q.front();Q.pop();
        for(int i=0;i<8;i++)
        {
            int a=t.x+dx[i],b=t.y+dy[i];
            if(a>0&&a<=n&&b<=m&&b>0&&g[a][b]!='*'&&dist[a][b]==-1)
            {
                dist[a][b]=dist[t.x][t.y]+1;
                ans=max(dist[a][b],ans);
                Q.push({a,b});                
            }
        }
    }
    return ans;
}
int main()
{
    ios::sync_with_stdio(false);
    cin>>m>>n>>X>>Y;
    bx=n+1-Y,by=X;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
            cin>>g[i][j];
    cout<<bfs()<<endl;
    return 0;
}