#include <bits/stdc++.h>
#define PII pair<int, int>
#define VI vector<int>
#define x first
#define y second

using namespace std;

void solve()
{
    int n, m;
    cin >> n >> m;
    vector a(n + 1, VI(m + 1));
    map<int, PII> mp;
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= m; j++)
        {
            cin >> a[i][j];
            mp[a[i][j]] = {i, j};
        }
    }
    int ans = -1;
    set<PII> st;
    for (int mex = 0; mex <= n * m; mex++)
    {
        auto [x, y] = mp[mex];
        if (st.size() <= 1)
        {
            st.insert({x, y});
            continue;
        }
        auto q = st.lower_bound({x, y});
        if (q == st.end())
        {
            q = prev(q);
            auto [l, r] = *q;
            if (x >= l && y >= r)
            {
                st.insert({x, y});
            }
            else
            {
                ans = mex;
                break;
            }
        }
        else if (q == st.begin())
        {
            auto [l, r] = *q;
            if (x <= l && y <= r)
            {
                st.insert({x, y});
            }
            else
            {
                ans = mex;
                break;
            }
        }
        else
        {
            auto q0 = prev(q);
            auto [l1, r1] = *q0;
            auto [l2, r2] = *q;
            if (x >= l1 && y >= r1 && x <= l2 && y <= r2)
            {
                st.insert({x, y});
            }
            else
            {
                ans = mex;
                break;
            }
        }
    }
    if (ans == -1)
    {
        cout << n * m << "\n";
    }
    else
        cout << ans << "\n";
}

signed main()
{
    int T;
    cin >> T;
    while (T--)
        solve();

    return 0;
}