#include <iostream>
#include <algorithm>
#include <set>
#include <map>
#include <vector>
#include <unordered_map>
#include <unordered_set>
#include <numeric>
#include <utility>
#include <array>

using namespace std;

int n, m;
vector<vector<int>> a;
vector<vector<pair<int, int>>> layers;

bool check(int mid){
    vector<pair<int, int>> v;
    for(int i = 0; i < n + m - 1; ++i){
        for(auto [x, y]: layers[i]){
            if(a[x][y] < mid){
                v.push_back({x, y});
            }
        }
    }

    for(int i = 0; i < (int)v.size() - 1; ++i){
        auto [x, y] = v[i];
        auto [x2, y2] = v[i + 1];

        if(x2 < x || y2 < y)
            return false;
    }
    return true;
}

void solve(){
    cin >> n >> m;

    a.resize(n, vector<int>(m));
    layers.clear();
    layers.resize(n + m - 1);

    for(int i = 0; i < n; ++i)
        for(int j = 0; j < m; ++j){
            cin >> a[i][j];
            layers[i + j].push_back({i, j});
        }

    int l = 0, r = n * m;
    while(l != r){
        int mid = (l + r + 1) >> 1;
        if(check(mid))
            l = mid;
        else
            r = mid - 1;
    }
    cout << l << "\n";
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    int t;
    cin >> t;

    while(t--){
        solve();
    }
}