#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<string>
#include<iostream>
#include<sstream>
#include<set>
#include<map>
#include<queue>
#include<bitset>
#include<vector>
#define SZ(X) ((int)(X).size())
#define ALL(X) (X).begin(), (X).end()
#define REP(I, N) for (int I = 0; I < (N); ++I)
#define REPP(I, A, B) for (int I = (A); I < (B); ++I)
#define RI(X) scanf("%d", &(X))
#define RII(X, Y) scanf("%d%d", &(X), &(Y))
#define RIII(X, Y, Z) scanf("%d%d%d", &(X), &(Y), &(Z))
#define DRI(X) int (X); scanf("%d", &X)
#define DRII(X, Y) int X, Y; scanf("%d%d", &X, &Y)
#define DRIII(X, Y, Z) int X, Y, Z; scanf("%d%d%d", &X, &Y, &Z)
#define RS(X) scanf("%s", (X))
#define CASET int ___T, case_n = 1; scanf("%d ", &___T); while (___T-- > 0)
#define MP make_pair
#define PB push_back
#define MS0(X) memset((X), 0, sizeof((X)))
#define MS1(X) memset((X), -1, sizeof((X)))
#define LEN(X) strlen(X)
#define PII pair<int,int>
#define VI vector<int>
#define VPII vector<pair<int,int> >
#define PLL pair<long long,long long>
#define VPLL vector<pair<long long,long long> >
#define F first
#define S second
typedef long long LL;
using namespace std;
const int MOD = 1e9+7;
const int SIZE = 1e6+10;
int N,M;
char s[555][555];
int xx[SIZE],yy[SIZE];
struct Union_Find{
    int d[SIZE],num[SIZE];
    void init(int n){
        REP(i,n)d[i]=i,num[i]=1;
    }
    int find(int x){
        return (x!=d[x])?(d[x]=find(d[x])):x;
    }
    bool uu(int x,int y){
        x=find(x);
        y=find(y);
        if(x==y)return 0;
        if(num[x]<=num[y]){
            num[y]+=num[x];
            d[x]=y;
        }
        else{
            num[x]+=num[y];
            d[y]=x;
        }
        return 1;
    }
}U;
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
bool Out(int x,int y){return x<0||y<0||x>=N||y>=M;}
int get(int x,int y){return x*M+y;}
int main(){
    CASET{
        RII(N,M);
        U.init(N*M+2);
        REP(i,N)RS(s[i]);
        DRI(Q);
        REP(i,Q){
            RII(xx[i],yy[i]);
            s[xx[i]][yy[i]]='1';
        }
        REP(i,N)REP(j,M){
            if(s[i][j]=='1')continue;
            if(i+1<N&&s[i+1][j]=='0')U.uu(get(i,j),get(i+1,j));
            if(j+1<M&&s[i][j+1]=='0')U.uu(get(i,j),get(i,j+1));
            if(!i)U.uu(N*M,get(i,j));
            if(i==N-1)U.uu(N*M+1,get(i,j));
        }
        if(U.find(N*M)==U.find(N*M+1))puts("-1");
        else{
            int an=0;
            for(int i=Q-1;i>=0;i--){
                int x=xx[i],y=yy[i];
                s[x][y]='0';
                if(!x)U.uu(N*M,get(x,y));
                if(x==N-1)U.uu(N*M+1,get(x,y));
                
                REP(k,4){
                    int nx=x+dx[k];
                    int ny=y+dy[k];
                    if(Out(nx,ny))continue;
                    if(s[nx][ny]=='1')continue;
                    U.uu(get(nx,ny),get(x,y));
                }
                if(U.find(N*M)==U.find(N*M+1)){
                    an=i+1;
                    break;
                }
            }
            printf("%d\n",an);
        }
    }
    return 0;
}