#include<iostream>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<algorithm>
#include<utility>

using namespace std;

#define int long long
#define endl "\n"

constexpr long long INF = (long long)1e18;
constexpr long long MOD = 1'000'000'007; 

struct fast_io {
	fast_io(){
		std::cin.tie(nullptr);
		std::ios::sync_with_stdio(false);
	};
} fio;

int dy[] = {0, 0, 1, 1};
int dx[] = {0, 1, 0, 1};

#define x first
#define y second

void print(int ny, int nx, vector<int> v){
    // cout<<" <><><> "<<" "<<ny<<" "<<nx<<endl;
    for(int i = 0; i < v.size(); i++){
        cout<<ny+dy[v[i]]+1<<" "<<nx+dx[v[i]]+1<<endl;
        // cout<<dy[v[i]]<<" "<<dx[v[i]]<<" "<<v[i]<<endl;
    }
}

signed main(){
	cout<<fixed<<setprecision(10);
	
    int T;
    
    cin>>T;
	
	for(int _ = 0; _ < T; _++){
        int N, M;
        
        cin>>N>>M;
        
        if(N%2 || M%2) {
            if(N == 1 && M == 1) {
                cout<<0<<endl;
                cout<<1<<" "<<1<<endl;
            } else {
                cout<<-1<<endl;
            }
        } else {
            cout<<N * M -1<<endl;
            
            // cout<<2<<" "<<1<<endl;
            
            for(int i = 0; i < M; i += 4){
                
                print(0, i, {2, 1, 0, 3});
                
                for(int j = 2; j < N; j += 2){
                    print(j, i, {1, 2, 0, 3});
                }
                
                if(i + 2 >= M) break;
                for(int j = N-2; j >= 2; j -= 2){
                    print(j, i+2, {2, 1, 3, 0});
                }
                
                print(0, i+2, {2, 1, 0, 3});
            }
        }
    }
	
	return 0;
}