#include <stdio.h>
#include <string.h>
#include <iostream>
#include <queue>
using namespace std;  const int MAXN = 500;
int Gra[MAXN + 7][MAXN + 7];
int Date[MAXN + 7][MAXN + 7];
int stpX[] = {1, 0, 0, -1};//下一个状态(方向)
int stpY[] = {0, 1, -1, 0};
int visited[MAXN + 7][MAXN + 7];//标记点是否被访问
int n, m;
int flag;struct Point{int x;int y;
}pt[MAXN * MAXN + 7];int chage(int x, int y)
{return (x - 1) * m + y;
}void BFS()//BFS判断连通性
{memset(visited, 0, sizeof(visited));queue<Point> ptQu;struct Point pi;for(int i = 1; i <= m ; i++)//枚举起点{if(Date[1][i] == 1 || visited[1][i]) continue;visited[1][i]= 1;pi.x = 1;pi.y = i;ptQu.push(pi);while(!ptQu.empty()){pi = ptQu.front();ptQu.pop();//cout << pi.x << " " <<pi.y<<endl;if(pi.x == n) {flag = 1;return;} //遍历到了最底下，说明连通for(int i = 0; i < 4; i++){int xx = pi.x + stpX[i];int yy = pi.y + stpY[i];if(Date[xx][yy] == 0 && !visited[xx][yy]){visited[xx][yy] = 1;struct Point temp;temp.x = xx, temp.y = yy;ptQu.push(temp);}}}}
}int isOk(int mid)
{memcpy(Date, Gra, sizeof(Gra));for(int i = 1; i <= mid; i++)Date[ pt[i].x ][ pt[i].y ] = 1;flag = 0;BFS();//cout << mid << endl;if(flag) return 0;return 1;
}int main()
{  //freopen("in.txt", "r", stdin);  int T;  scanf("%d",&T);  while(T--)  {  scanf("%d%d",&n, &m);  memset(Gra, -1, sizeof(Gra));memset(&pt, 0, sizeof(Point));  for(int i = 1; i <= n; i++ )for(int j = 1; j <= m; j++)   scanf("%1d",&Gra[i][j]);int Q;  scanf("%d",&Q);  for(int i = 1; i <= Q; i++){int xx, yy;scanf("%d%d", &xx, &yy);pt[i].x = xx + 1;pt[i].y = yy + 1;}int lo =0;int hi = Q;while(lo <= hi)//二分求解{int mid = (lo + hi) >> 1;if(isOk(mid)) hi = mid - 1;else lo = mid + 1;//printf("%d %d\n",lo, hi);
        }if(hi == Q)printf("-1\n");else printf("%d\n", lo);}  return 0;
}