#include <iostream>

#include <cstdio>

using namespace std;

int fx[]={,,-,},fy[]={,-,,};

int Answer,n,m,x,y,i,j;

char atlas[][],what;

bool vis[][];

void ss(int u,int v)

{

    Answer++;

    vis[u][v]=;

    for(int i=;i<;++i)

    {

        int mx=u+fx[i],my=v+fy[i];

        if(mx>&&mx<=n&&my>&&my<=m&&atlas[mx][my]==atlas[x][y]&&!vis[mx][my])

        ss(mx,my);

    }

}

int main()

{

    scanf("%d%d%d%d",&n,&m,&x,&y);

    for(i=;i<=n;++i)

        for(j=;j<=m;++j)

            cin>>atlas[i][j];

    ss(x,y);

    printf("%d",Answer);

    return ;

}