// >>> TEMPLATES
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
#define int ll
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
#define repR(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep1R(i, n) for (int i = (int)(n); i >= 1; i--)
#define loop(i, a, B) for (int i = a; i B; i++)
#define loopR(i, a, B) for (int i = a; i B; i--)
#define all(x) begin(x), end(x)
#define allR(x) rbegin(x), rend(x)
#define rng(x, l, r) begin(x) + (l), begin(x) + (r)
#define pb push_back
#define eb emplace_back
#define fst first
#define snd second
template <class A, class B> auto mp(A &&a, B &&b) { return make_pair(forward<A>(a), forward<B>(b)); }
template <class... T> auto mt(T&&... x) { return make_tuple(forward<T>(x)...); }
template <class Int> auto constexpr inf_ = numeric_limits<Int>::max()/2-1;
auto constexpr INF32 = inf_<int32_t>;
auto constexpr INF64 = inf_<int64_t>;
auto constexpr INF   = inf_<int>;
#ifdef LOCAL
#include "debug.hpp"
#else
#define dump(...) (void)(0)
#define say(x) (void)(0)
#define debug if (0)
#endif
template <class T, class Comp> struct pque : priority_queue<T, vector<T>, Comp> { vector<T> &data() { return this->c; } void clear() { this->c.clear(); } };
template <class T> using pque_max = pque<T, less<T>>;
template <class T> using pque_min = pque<T, greater<T>>;
template <class T, class = typename T::iterator, enable_if_t<!is_same<T, string>::value, int> = 0>
ostream& operator<<(ostream& os, T const& a) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, size_t N, enable_if_t<!is_same<T, char>::value, int> = 0>
ostream& operator<<(ostream& os, const T (&a)[N]) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, class = decltype(begin(declval<T&>())), class = typename enable_if<!is_same<T, string>::value>::type>
istream& operator>>(istream& is, T &a) { for (auto& x : a) is >> x; return is; }
template <class T, class S> ostream& operator<<(ostream& os, pair<T, S> const& p) { return os << p.first << " " << p.second; }
template <class T, class S> istream& operator>>(istream& is, pair<T, S>& p) { return is >> p.first >> p.second; }
struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup;
template <class F> struct FixPoint : private F {
    constexpr FixPoint(F&& f) : F(forward<F>(f)) {}
    template <class... T> constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward<T>(x)...); }
};
struct MakeFixPoint { template <class F> constexpr auto operator|(F&& f) const { return FixPoint<F>(forward<F>(f)); } };
#define MFP MakeFixPoint()|
#define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__)
template <class T, size_t d> struct vec_impl {
    using type = vector<typename vec_impl<T, d-1>::type>;
    template <class... U> static type make_v(size_t n, U&&... x) { return type(n, vec_impl<T, d-1>::make_v(forward<U>(x)...)); }
};
template <class T> struct vec_impl<T, 0> { using type = T; static type make_v(T const& x = {}) { return x; } };
template <class T, size_t d = 1> using vec = typename vec_impl<T, d>::type;
template <class T, size_t d = 1, class... Args> auto make_v(Args&&... args) { return vec_impl<T, d>::make_v(forward<Args>(args)...); }
template <class T> void quit(T const& x) { cout << x << endl; exit(0); }
template <class T, class U> constexpr bool chmin(T& x, U const& y) { if (x > y) { x = y; return true; } return false; }
template <class T, class U> constexpr bool chmax(T& x, U const& y) { if (x < y) { x = y; return true; } return false; }
template <class It> constexpr auto sumof(It b, It e) { return accumulate(b, e, typename iterator_traits<It>::value_type{}); }
template <class T> int sz(T const& x) { return x.size(); }
template <class C, class T> int lbd(C const& v, T const& x) { return lower_bound(begin(v), end(v), x)-begin(v); }
template <class C, class T> int ubd(C const& v, T const& x) { return upper_bound(begin(v), end(v), x)-begin(v); }
int64_t mod(int64_t x, int64_t m) { assert(m != 0); return (x %= m) < 0 ? x+m : x; }
const int dx[] = { 1, 0, -1, 0, 1, -1, -1, 1 };
const int dy[] = { 0, 1, 0, -1, 1, 1, -1, -1 };
constexpr int popcnt(ll x) { return __builtin_popcountll(x); }
template <class A, class B> pair<A, B> operator+(pair<A, B> const& p, pair<A, B> const& q) { return { p.first + q.first, p.second + q.second }; }
template <class A, class B> pair<A, B> operator-(pair<A, B> const& p, pair<A, B> const& q) { return { p.first - q.first, p.second - q.second }; }
mt19937_64 seed_{random_device{}()};
template <class Int> Int rand(Int a, Int b) { return uniform_int_distribution<Int>(a, b)(seed_); }
i64 irand(i64 a, i64 b) { return rand<i64>(a, b); } // [a, b]
u64 urand(u64 a, u64 b) { return rand<u64>(a, b); } //
template <class It> void shuffle(It l, It r) { shuffle(l, r, seed_); }
// <<<

auto solve() {
    int n, m; cin >> n >> m;

    if (n == 1 and m == 1) {
        cout << "0\n";
        cout << "1 1\n";
        return;
    }
    if (n % 2 == 1 or m % 2 == 1) {
        cout << "-1\n";
        return;
    }

    vector<pair<int, int>> pos;
    int x = 0, y = 1;
    pos.eb(x, y);
    rep (i, n/2) {
        if (i % 2 == 0) {
            rep (j, m/2) {
                if (j == 0) {
                    pos.eb(++x, --y);
                    pos.eb(--x, y);
                    pos.eb(++x, ++y);
                    if (j+1 < m/2) {
                        pos.eb(x, ++y);
                    } else {
                        pos.eb(++x, y);
                    }
                } else {
                    pos.eb(--x, ++y);
                    pos.eb(x, --y);
                    pos.eb(++x, ++y);
                    if (j+1 < m/2) {
                        pos.eb(x, ++y);
                    } else {
                        pos.eb(++x, y);
                    }
                }
            }
        } else {
            repR (j, m/2) {
                if (j == 0) {
                    pos.eb(++x, --y);
                    pos.eb(--x, y);
                    pos.eb(++x, ++y);
                    pos.eb(++x, y);
                } else {
                    pos.eb(++x, --y);
                    pos.eb(x, ++y);
                    pos.eb(--x, --y);
                    pos.eb(x, --y);
                }
            }
        }
    }
    pos.pop_back();

    cout << n*m-1 << "\n";
    for (auto [x, y] : pos) cout << x+1 << " " << y+1 << "\n";

    debug {
        auto a = make_v<int, 2>(n, m);
        int x = -1, y = -1;
        int i = 0;
        for (auto [nx, ny] : pos) {
            assert(0 <= nx); assert(nx < n);
            assert(0 <= ny); assert(ny < m);
            if (x >= 0 and y >= 0) {
                if (i % 2 == 0) {
                    dump(i, x, y, nx, ny);
                    assert(abs(x-nx) == 1 and abs(y-ny) == 1);
                } else {
                    assert(abs(x-nx) + abs(y-ny) == 1);
                }
                i++;
            }
            a[nx][ny]++;
            x = nx, y = ny;
        }
        dump(as_mat(a));
        rep (i, n) rep (j, m) assert(a[i][j] == 1);
    }

}

int32_t main() {
    int t; cin >> t;
    while (t--) {
        solve();
//        cout << (solve() ? "YES" : "NO") << "\n";
        debug { cerr << endl; }
    }
}