#include<iostream>
#include<cstdio>
#include<queue>
using namespace std;
const int MX=100010;
const int inf=0x3fffffff;

int T, N, M, K;
int p[MX];
int read()
{
	int r=0, f=1; char ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-') f=-1; ch=getchar();}
	while(ch>='0'&&ch<='9') {r=r*10+ch-'0'; ch=getchar();}
	return r*f;
}
priority_queue<int> q[MX];
int main()
{
	// freopen("testdata.in","r",stdin);
	T=read();
	while(T--)
	{
		N=read(); M=read(); K=read();
		for(int i=1;i<=N;i++) 
			while(!q[i].empty()) q[i].pop();
		for(int i=1;i<=N*M;i++) 
		{
			p[i]=read();
			q[(p[i]-1)/M+1].emplace(i);
		}
		int ans=inf;
		for(int i=1;i<=N;i++)
		{
			int tag=0, t=K;
			while(!q[i].empty())
			{
				int x=q[i].top(); q[i].pop();
				// cout << "x=" << x << '\n';
				if(t==0) {ans=min(ans,x); tag=1; break;}
				else t--;
			}
			if(!tag) ans=min(ans,M);
		}
		cout << ans << '\n';
	}
	return (0-0);
}