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

using ll = long long;
#define fi first
#define se second
#define pb push_back

int main(){
  int t;
  cin>>t;
  while(t--){
    int n,m;
    cin>>n>>m;  
    if(n==1&&m==1){
      cout<<"0"<<endl;
      cout<<"1 1"<<endl;
    }
    else if(n%2==0&&m%2==0){
      cout<<n*m-1<<endl;
      int nowi=1,nowj=1;
      for(int i=0;i<(n*m)/4;i++){
        if(nowi%2==1){
          if(nowj!=m/2){
            cout<<nowi*2-1<<" "<<nowj*2-1<<endl;
            cout<<nowi*2<<" "<<nowj*2<<endl;
            cout<<nowi*2<<" "<<nowj*2-1<<endl;
            cout<<nowi*2-1<<" "<<nowj*2<<endl;
            nowj+=1;
          }
          else{
            cout<<nowi*2-1<<" "<<nowj*2-1<<endl;
            cout<<nowi*2<<" "<<nowj*2<<endl;
            cout<<nowi*2-1<<" "<<nowj*2<<endl;
            cout<<nowi*2<<" "<<nowj*2-1<<endl;
            nowi+=1;
          }
        }
        else{
          if(nowj==m/2){
            cout<<nowi*2-1<<" "<<nowj*2-1<<endl;
            cout<<nowi*2<<" "<<nowj*2<<endl;
            cout<<nowi*2-1<<" "<<nowj*2<<endl;
            cout<<nowi*2<<" "<<nowj*2-1<<endl;
            if(nowj==1){
              nowi+=1;
            }
            else{
              nowj-=1;
            }
          }
          else if(nowj!=1){
            cout<<nowi*2<<" "<<nowj*2<<endl;
            cout<<nowi*2-1<<" "<<nowj*2-1<<endl;
            cout<<nowi*2-1<<" "<<nowj*2<<endl;
            cout<<nowi*2<<" "<<nowj*2-1<<endl;
            nowj-=1;
          }
          else{
            cout<<nowi*2<<" "<<nowj*2<<endl;
            cout<<nowi*2-1<<" "<<nowj*2-1<<endl;
            cout<<nowi*2-1<<" "<<nowj*2<<endl;
            cout<<nowi*2<<" "<<nowj*2-1<<endl;
            nowi+=1;
          }
        }
      }
    }
    else{
      cout<<-1<<endl;
    }
  }
}