/**
 *    title:  kk.cpp
 *    author:  Proaes Meluam
 *    created:  2024-11-15 21:13:58
**/
#include <bits/stdc++.h>
#ifdef LOCAL
#include "algo/debug.h" 
#else
#define debug(...) 42
#endif
using namespace std;
using ll = long long;
using ull = unsigned long long;
const double pi = acos(-1);
const double E = exp(1);
constexpr ll mod = 1e9 + 7;
// constexpr int inf = 0x3f3f3f3f;
constexpr ll inf = 0x3f3f3f3f3f3f3f3f;
int main() {
    cin.tie(nullptr)->sync_with_stdio(false);

    int tt = 1;
    cin >> tt;
    while (tt--) {
        int n, m, k;
        cin >> n >> m >> k;
        vector<vector<int>> p(n + 1, vector<int>(m + 1));
        vector<int> cnt(n + 1);
        for (int i = 1; i <= n; ++ i) {
            for (int j = 1; j <= m; ++ j) {
                cin >> p[i][j];
            }
        }
        int ans = m, cur = 1;
        for (int i = 1; i <= n; ++ i) {
            for (int j = 1; j <= m; ++ j, ++ cur) {
                int row = (p[i][j] - 1) / m + 1;
                // debug(row);
                cnt[row]++;
                if (cnt[row] + k >= m) {
                    // debug("?");
                    ans = max(m, cur);
                    break;
                }
            }
        }
        cout << ans << "\n";
    }
}