#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <queue>
using namespace std;

int n,m,k;
char graph[55][55];
int dx[55],dy[55];
bool vis[55][55];
int step[55][55];
int sx,sy;

struct node{
    int x,y;
    int step;
};

void bfs(){
    queue<node> q;
    node tmp;
    tmp.x = sx;
    tmp.y = sy;
    graph[sx][sy] = 'X';
    int res = 0;
    tmp.step = 0;
    q.push(tmp);
    while(!q.empty()){
        node cur = q.front();
        q.pop();
        for(int i=0;i<k;i++){
            int xx = cur.x+dx[i];
            int yy = cur.y+dy[i];
            if(xx>=0 && xx<n && yy>=0 && yy<m && graph[xx][yy]=='.'){
                graph[xx][yy] = 'X';
                node t;
                t.x = xx;
                t.y = yy;
                t.step = cur.step+1;
                step[xx][yy] = t.step;
                q.push(t);
                res = max(res,t.step);
            }
        }
    }
    for(int i=0;i<n;i++){
        for(int j=0;j<m;j++){
            if(graph[i][j]=='.'){
                printf("-1\n");
                return ;
            }
        }
    }
    printf("%d\n",res);
}

int main(){
    scanf("%d%d",&n,&m);
    for(int i=0;i<n;i++)
        scanf("%s",graph[i]);
    scanf("%d%d",&sx,&sy);
    memset(vis,false,sizeof(vis));
    memset(step,0,sizeof(step));
    scanf("%d",&k);
    for(int i=0;i<k;i++){
        scanf("%d%d",dx+i,dy+i);
    }
    bfs();
    return 0;
}