#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }

struct UnionFind {
    vector<int> data;
    void init(int n) { data.assign(n, -1); }
    bool unionSet(int x, int y) {
        x = root(x); y = root(y);
        if(x != y) {
            if(data[y] < data[x]) swap(x, y);
            data[x] += data[y]; data[y] = x;
        }
        return x != y;
    }
    bool findSet(int x, int y) { return root(x) == root(y); }
    int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); }
    int size(int x) { return -data[root(x)]; }
};

int N, M;
UnionFind uf;
vector<vi> cnt;
void process(int i, int j) {
    if(cnt[i][j] != 0) return;
    static const int dy[4] = { 0, 1, 0, -1 }, dx[4] = { 1, 0, -1, 0 };
    for(int d = 0; d < 4; ++ d) {
        int yy = i + dy[d], xx = j + dx[d];
        if(yy < 0) {
            uf.unionSet(i * M + j, N * M);
            continue;
        }
        if(yy >= N) {
            uf.unionSet(i * M + j, N * M + 1);
            continue;
        }
        if(yy < 0 || yy >= N || xx < 0 || xx >= M) continue;
        if(cnt[yy][xx] != 0) continue;
        uf.unionSet(i * M + j, yy * M + xx);
    }
};

int main() {
    int T;
    scanf("%d", &T);
    for(int ii = 0; ii < T; ++ ii) {
        scanf("%d%d", &N, &M);
        cnt.assign(N, vi(M));
        rep(i, N) {
            char buf[501];
            scanf("%s", buf);
            rep(j, M)
                cnt[i][j] = buf[j] - '0';
        }
        int Q;
        scanf("%d", &Q);
        vector<int> X(Q);
        vector<int> Y(Q);
        for(int i = 0; i < Q; ++ i)
            scanf("%d%d", &X[i], &Y[i]);
        rep(i, Q)
            ++ cnt[X[i]][Y[i]];
        uf.init(N * M + 2);
        rep(i, N) rep(j, M)
            process(i, j);
        int ans = Q;
        if(!uf.findSet(N * M, N * M + 1)) {
            for(-- ans; ans >= 0; -- ans) {
                -- cnt[X[ans]][Y[ans]];
                process(X[ans], Y[ans]);
                if(uf.findSet(N * M, N * M + 1))
                    break;
            }
        }
        printf("%d\n", ans == Q ? -1 : ans + 1);
    }
    return 0;
}