#include<bits/stdc++.h>
using namespace std;

const int N = 30;

int p[N];
void init()
{
    for(int i = 0;i<=N;i++)
    {
        p[i] = i;
    }
    
}
int find(int x)  // 并查集
{
    if (p[x] != x) p[x] = find(p[x]);
    return p[x];
}
void merge(int x,int y)
{
    x = find(x),y = find(y);
    if(x!=y)
    {
        p[x] = p[y];
    }
}

int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        int n, m, k;
        cin >> n >> m >> k;
        vector<int> a(n * m);
        for(int i = 0; i < n * m; i++){
            cin >> a[i];
        }
        int l = m;
        int r = n * m;
        int mid;
        auto check = [&](int x){
            vector<int> st(n);
            int cnt = 0;
            for(int i = 0; i < x; i++){
                st[a[i] / m]++;
                cnt = max(cnt, st[a[i] / m]);
            }
            if(cnt + k >= m) return 1;
            return 0;
        };
        
        while(l < r){
            mid = (l + r) >> 1;
            if(check(mid)) r = mid;
            else l = mid + 1;
        }
        cout << l << endl;
    }
}