#include<cstdio>
#include<cstring>
#include<cassert>
#include<vector>
#include<list>
#include<queue>
#include<map>
#include<set>
#include<deque>
#include<stack>
#include<bitset>
#include<algorithm>
#include<functional>
#include<numeric>
#include<utility>
#include<sstream>
#include<iostream>
#include<iomanip>
#include<cmath>
#include<cstdlib>
#include<ctime>
#include<fstream>
#include<typeinfo>
#include<locale>
#include<iterator>
#include<valarray>
#include<complex>
#include<climits>

using namespace std;

#define xx         first
#define yy         second
#define pb         push_back
#define mp         make_pair
#define LL         long long
#define inf        INT_MAX/3
#define mod        1000000007ll
#define PI         acos(-1.0)
#define linf       (1ll<<60)-1
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)
#define REP(I,N)   FOR(I,0,N)
#define ALL(A)     ((A).begin(), (A).end())
#define set0(ar)   memset(ar,0,sizeof ar)
#define vsort(v)   sort(v.begin(),v.end())
#define setinf(ar) memset(ar,126,sizeof ar)

//cout << fixed << setprecision(20) << p << endl;

template <class T> inline T bigmod(T p,T e,T M){
    LL ret = 1;
    for(; e > 0; e >>= 1){
        if(e & 1) ret = (ret * p) % M;
        p = (p * p) % M;
    } return (T)ret;
}
template <class T> inline T gcd(T a,T b){if(b==0)return a;return gcd(b,a%b);}
template <class T> inline T modinverse(T a,T M){return bigmod(a,M-2,M);}

int nxt[4][2] = { {-1, 0}, {0, -1}, {1, 0}, {0, 1} };
int pre[511*511], id[511][511];
pair < int, int > pp[500 * 501];

int Find(int x){
    if(x == pre[x]) return x;
    return pre[x] = Find(pre[x]);
}

string ss[501];


int main() {
//    ios_base::sync_with_stdio(0); cin.tie(0);
    int T; cin >> T;
    while(T--){
        int n, m; cin >> n >> m;
        int cnt = 1;
        FOR(i, 1, m+1) id[0][i] = 1;
        REP(i, n){
            cin >> ss[i+1];
            REP(j, m) id[i+1][j+1] = ++cnt;
        }

        cnt++;
        FOR(i, 1, m+1) id[n+1][i] = cnt;

        FOR(i, 1, cnt+1) pre[i] = i;

        int Q; cin >> Q;
        REP(i, Q){
            cin >> pp[i+1].xx >> pp[i+1].yy;
            pp[i+1].xx++;
            pp[i+1].yy++;
            ss[pp[i+1].xx][pp[i+1].yy - 1] = '1';
        }

        FOR(i, 1, n+1){
            FOR(j, 1, m+1){
                if(ss[i][j-1] == '1') continue;
                REP(k, 4){
                    int x = i + nxt[k][0], y = j + nxt[k][1];
                    if(y == 0 || y > m || (x > 0 && x <= n && ss[x][y-1] == '1')) continue;
                    int px = Find(id[x][y]), py = Find(id[i][j]);
                    if(px == py) continue;
                    pre[px] = py;
                }
            }
        }

        if(Find(cnt) == Find(1)){
            cout << -1 << endl;
            continue;
        }
        int fl = 0;
        for(int i = Q; i >= 1; i--){
            ss[pp[i].xx][pp[i].yy - 1] = '0';
            REP(k, 4){
                int x = pp[i].xx + nxt[k][0], y = pp[i].yy + nxt[k][1];
                if(y == 0 || y > m || (x > 0 && x <= n && ss[x][y-1] == '1')) continue;
                int px = Find(id[x][y]), py = Find(id[pp[i].xx][pp[i].yy]);
                if(px == py) continue;
                pre[px] = py;
            }

            if(Find(cnt) == Find(1)){
                fl = i;
                break;
            }
        }

        cout << fl << endl;
    }
}