#include<bits/stdc++.h>
#define trig 50

using namespace std;

int main(){
  int T,R;
  cin >> T >> R;
  int p=0;
  vector<pair<int,int>> bk;
  for(int i=0;i<T;i++){
    vector<pair<int,int>> act;
    int N;
    cin >> N;
    for(int j=0;j<N;j++){
      p++;
      int v;
      cin >> v;
      bk.push_back({v,p});
      if(bk.size()==trig){
        sort(bk.begin(),bk.end());
        for(int k=0;k<trig;k++){
          if(k%4==0){continue;}
          act.push_back({bk[k-1].second,bk[k].second});
        }
        bk.clear();
      }
    }
    cout << act.size() << '\n';
    for(auto &nx : act){
      cout << nx.first << ' ' << nx.second << '\n';
    }
    fflush(stdout);
  }
  return 0;
}