#include <stdio.h>
#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <algorithm>

using ll = long long int;
using P = std::pair<int, int>;
using E = std::pair<P, int>;
const int INF = (1<<30);
const ll INFLL = (1ll<<60);
const ll MOD = 998244353ll;

#define l_ength size

void mul_mod(ll& a, ll b){
	a *= b;
	a %= MOD;
}

void add_mod(ll& a, ll b){
	a = (a<MOD)?a:(a-MOD);
	b = (b<MOD)?b:(b-MOD);
	a += b;
	a = (a<MOD)?a:(a-MOD);
}

std::vector<P> v,ans;

int main(void){
	int t,r,m=0,i,n,s,j,p;
	std::cin >> t >> r;
	for(i=0; i<t; ++i){
		std::cin >> n;
		for(j=0; j<n; ++j){
			std::cin >> s; ++m;
			v.push_back(P(s,m));
		}
		std::sort(v.begin(),v.end());
		p = 1;
		for(i=0; i<v.l_ength(); ++i){
			if(p == r){
				p = 1;
				continue;
			}
			ans.push_back(P(v[i-1].second,v[i].second));
		}
		std::cout << ans.l_ength() << std::endl;
		for(i=0; i<ans.l_ength(); ++i){
			std::cout << ans[i].first << " " << ans[i].second << std::endl;
		}
		v.clear(); ans.clear();
	}
	return 0;
}