#include <bits/stdc++.h>
using namespace std;
int main(){
  int T;
  cin >> T;
  for (int i = 0; i < T; i++){
    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;
      vector<int> x, y;
      for (int j = 0; j < N; j += 2){
        for (int k = 0; k < M; k++){
          if (k % 4 == 0 || k % 4 == 3){
            x.push_back(j);
          } else {
            x.push_back(j + 1);
          }
          y.push_back(k);
        }
        for (int k = M - 1; k >= 0; k--){
          if (k % 4 == 1 || k % 4 == 2){
            x.push_back(j);
          } else {
            x.push_back(j + 1);
          }
          y.push_back(k);
        }
      }
      for (int j = 0; j < N * M; j++){
        cout << x[j] + 1 << ' ' << y[j] + 1 << endl;
      }
    } else {
      cout << -1 << endl;
    }
  }
}