// >>> 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; } } }