#include<bits/stdc++.h>

using namespace std;

int main(){
  int T,R;
  cin >> T >> R;
  int p=0,nxt=4;
  for(int i=0;i<T;i++){
    int n;
    cin >> n;
    for(int j=0;j<n;j++){
      int dum;
      cin >> dum;
    }
    p+=n;
    vector<pair<int,int>> vp;
    while(nxt<=p){
      vp.push_back({nxt-3,nxt-2});
      vp.push_back({nxt-2,nxt-1});
      vp.push_back({nxt-1,nxt});
      nxt+=4;
    }
    cout << vp.size() << '\n';
    for(auto &nx : vp){
      cout << nx.first << ' ' << nx.second << '\n';
    }
    fflush(stdout);
  }
  return 0;
}