#define LOCAL
#include <bits/stdc++.h>
using namespace std;
#pragma region Macros
typedef long long ll;
typedef __int128_t i128;
typedef unsigned int uint;
typedef unsigned long long ull;
#define ALL(x) (x).begin(), (x).end()

template <typename T> istream& operator>>(istream& is, vector<T>& v) {
    for (T& x : v) is >> x;
    return is;
}
template <typename T> ostream& operator<<(ostream& os, const vector<T>& v) {
    for (int i = 0; i < (int)v.size(); i++) {
        os << v[i] << (i + 1 == (int)v.size() ? "" : " ");
    }
    return os;
}
template <typename T, typename U> ostream& operator<<(ostream& os, const pair<T, U>& p) {
    os << '(' << p.first << ',' << p.second << ')';
    return os;
}
template <typename T, typename U, typename V> ostream& operator<<(ostream& os, const tuple<T, U, V>& t) {
    os << '(' << get<0>(t) << ',' << get<1>(t) << ',' << get<2>(t) << ')';
    return os;
}
template <typename T, typename U, typename V, typename W> ostream& operator<<(ostream& os, const tuple<T, U, V, W>& t) {
    os << '(' << get<0>(t) << ',' << get<1>(t) << ',' << get<2>(t) << ',' << get<3>(t) << ')';
    return os;
}
template <typename T, typename U> ostream& operator<<(ostream& os, const map<T, U>& m) {
    os << '{';
    for (auto itr = m.begin(); itr != m.end();) {
        os << '(' << itr->first << ',' << itr->second << ')';
        if (++itr != m.end()) os << ',';
    }
    os << '}';
    return os;
}
template <typename T, typename U> ostream& operator<<(ostream& os, const unordered_map<T, U>& m) {
    os << '{';
    for (auto itr = m.begin(); itr != m.end();) {
        os << '(' << itr->first << ',' << itr->second << ')';
        if (++itr != m.end()) os << ',';
    }
    os << '}';
    return os;
}
template <typename T> ostream& operator<<(ostream& os, const set<T>& s) {
    os << '{';
    for (auto itr = s.begin(); itr != s.end();) {
        os << *itr;
        if (++itr != s.end()) os << ',';
    }
    os << '}';
    return os;
}
template <typename T> ostream& operator<<(ostream& os, const multiset<T>& s) {
    os << '{';
    for (auto itr = s.begin(); itr != s.end();) {
        os << *itr;
        if (++itr != s.end()) os << ',';
    }
    os << '}';
    return os;
}
template <typename T> ostream& operator<<(ostream& os, const unordered_set<T>& s) {
    os << '{';
    for (auto itr = s.begin(); itr != s.end();) {
        os << *itr;
        if (++itr != s.end()) os << ',';
    }
    os << '}';
    return os;
}
template <typename T> ostream& operator<<(ostream& os, const deque<T>& v) {
    for (int i = 0; i < (int)v.size(); i++) {
        os << v[i] << (i + 1 == (int)v.size() ? "" : " ");
    }
    return os;
}

void debug_out() { cerr << '\n'; }
template <class Head, class... Tail> void debug_out(Head&& head, Tail&&... tail) {
    cerr << head;
    if (sizeof...(Tail) > 0) cerr << ", ";
    debug_out(move(tail)...);
}
#ifdef LOCAL
#define debug(...)                                                                   \
    cerr << " ";                                                                     \
    cerr << #__VA_ARGS__ << " :[" << __LINE__ << ":" << __FUNCTION__ << "]" << '\n'; \
    cerr << " ";                                                                     \
    debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

template <typename T> T gcd(T x, T y) { return y != 0 ? gcd(y, x % y) : x; }
template <typename T> T lcm(T x, T y) { return x / gcd(x, y) * y; }

template <class T1, class T2> inline bool chmin(T1& a, T2 b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template <class T1, class T2> inline bool chmax(T1& a, T2 b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
#pragma endregion

const int INF = 1e9;
const long long IINF = 1e18;
const char dir[4] = {'D', 'R', 'U', 'L'};
const long long MOD = 1000000007;
// const long long MOD = 998244353;

const int dx[3][4] = {{0, 1, 1, 0}, {1, 0, 0, 1}, {0, 1, 0, 1}}, dy[3][4] = {{0, 1, 0, 1}, {1, 0, 1, 0}, {0, 1, 1, 0}};

void solve() {
    int N, M;
    cin >> N >> M;

    if (N == 1 && M == 1) {
        cout << 0 << '\n';
        cout << 1 << ' ' << 1 << '\n';
        return;
    }

    if ((N & 1) || (M & 1)) {
        cout << -1 << '\n';
        return;
    }

    int x = 0, y = 0;
    vector<pair<int, int>> ans;

    if (N == 2) {
        while ((int)ans.size() < N * M) {
            for (int i = 0; i < 4; i++) ans.emplace_back(x + dx[0][i] + 1, y + dy[0][i] + 1);
            y += 2;
        }
    } else if (M == 2) {
        while ((int)ans.size() < N * M) {
            for (int i = 0; i < 4; i++) ans.emplace_back(x + dx[1][i] + 1, y + dy[1][i] + 1);
            x += 2;
        }
    } else {
        while ((int)ans.size() < N * M) {
            int cur, nx, ny;
            if (x % 4 == 0) {
                if (y == M - 2) {
                    cur = 2;
                    nx = 2, ny = 0;
                } else {
                    cur = 0;
                    nx = 0, ny = 2;
                }
            } else {
                if (y == M - 2) {
                    cur = 2;
                    nx = 0, ny = -2;
                } else if (y == 0) {
                    cur = 1;
                    nx = 2, ny = 0;
                } else {
                    cur = 1;
                    nx = 0, ny = -2;
                }
            }
            for (int i = 0; i < 4; i++) ans.emplace_back(x + dx[cur][i] + 1, y + dy[cur][i] + 1);
            x += nx, y += ny;
            // debug(cur, x, y);
        }
    }

    cout << ans.size() - 1 << '\n';
    for (auto p : ans) cout << p.first << ' ' << p.second << '\n';
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int T;
    cin >> T;
    for (; T--;) solve();
    return 0;
}