#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
#define pii pair<int, int>

int n, m, k;
inline pii get(int x)
{
    // x = (i - 1) * m + j;
    int j = x % m;
    if (j == 0)
        j = m;
    int i = (x - j) / m + 1;
    return make_pair(i, j);
}

int vis[100100], p[100100];

inline bool check(int x)
{
    for (int i = 1; i <= m; ++i)
        vis[i] = 0;
    int Max = 0, id = 0;
    for (int i = 1; i <= x; ++i)
    {
        pii tmp = get(p[i]);
        vis[tmp.first]++;
        if (vis[tmp.first] > Max)
            Max = vis[tmp.first], id = tmp.first;
    }
    if (m - vis[id] <= k)
    {
        // cout << x << ' ' << m << ' ' << id << ' ' << vis[id] << ' ' << k << " ??\n";
        return 1;
    }
    else
        return 0;
}

void Solve()
{
    cin >> n >> m >> k;
    for (int i = 1; i <= n * m; ++i)
    {
        cin >> p[i];
    }
    int l = m, r = n * m;
    while (l < r - 1)
    {
        int mid = l + r >> 1;
        if (check(mid))
            r = mid;
        else
            l = mid;
    }
    // cout << l << ' ' << r << ' ' << check(l) << ' ' << check(r) << " !!\n";
    if (check(l))
        cout << l << endl;
    else
        cout << r << endl;
}
signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int T = 1;
    cin >> T;
    while (T--)
        Solve();
}