#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using namespace atcoder;

int solve(){
	int n, m;
	cin >> n >> m;
	bool FLIP = false;
	auto v2 = [&](int x){
		int res = 0;
		while(x % 2 == 0){
			res++;
			x /= 2;
		}
		return res;
	};
	if(v2(n) + v2(m) <= 2){
		cout << "-1" << endl;
		return 0;
	}
	if(v2(n) > v2(m)){
		swap(n, m);
		FLIP = true;
	}
	
	int cnt = 0;
	vector<vector<int>> a(n, vector<int>(m));
	vector<vector<int>> B = {{1, 1, 1, 2}, {1, 2, 2, 2}};
	auto set_B = [&](int si, int sj){
		rep(di, 2) rep(dj, 4){
			a[si + di][sj + dj] = cnt + B[di][dj];
		}
		cnt += 2;
	};
	vector<vector<int>> C = {{1, 1, 3, 3, 3, 4, 6, 6}, {1, 2, 3, 4, 4, 4, 5, 6}, {1, 2, 2, 2, 5, 5, 5, 6}};
	auto set_C = [&](int si, int sj){
		rep(di, 3) rep(dj, 8){
			a[si + di][sj + dj] = cnt + C[di][dj];
		}
		cnt += 6;
	};
	
	
	// case (II)
	if(v2(n) >= 1 and v2(m) >= 2){
		int k = n * m / 4;
		rep(i, n / 2) rep(j, m / 4){
			set_B(i * 2, j * 4);
		}
		cout << k << endl;
		if(FLIP){
			vector<vector<int>> a_old(m, vector<int>(n));
			swap(a, a_old);
			rep(i, n) rep(j, m) a[j][i] = a_old[i][j];
			swap(n, m);
		}
		rep(i, n){
			rep(j, m){
				cout << a[i][j];
				if(j == m - 1) cout << endl;
				cout << ' ';
			}
		}
		return 0;
	}
	// case (III)
	if(v2(n) == 0 and v2(m) >= 3){
		if(n == 1){
			cout << "-1" << endl;
			return 0;
		}
		int k = n * m / 4;
		int n2 = n / 2 - 1;
		int m2 = m / 4;
		rep(i, n / 2 - 1) rep(j, m / 4){
			set_B(i * 2, j * 4);
		}
		rep(j, m / 8){
			set_C(n - 3, j * 8);
		}
		cout << k << endl;
		if(FLIP){
			vector<vector<int>> a_old(m, vector<int>(n));
			swap(a, a_old);
			rep(i, n) rep(j, m) a[j][i] = a_old[i][j];
			swap(n, m);
		}
		rep(i, n){
			rep(j, m){
				cout << a[i][j];
				if(j == m - 1) cout << endl;
				cout << ' ';
			}
		}
		return 0;
	}
	
	assert(false);
	return 0;
}

int main(){
	int t;
	cin >> t;
	for(int i = 0; i < t; i++) solve();
}