import java.util.*;

public class Main {

    public static final int MOD998 = 998244353;
    public static final int MOD100 = 1000000007;

    public static void main(String[] args) throws Exception {
        ContestScanner sc = new ContestScanner();
        ContestPrinter cp = new ContestPrinter();
        int T = sc.nextInt();
        for (int t = 0; t < T; t++) {
            // System.err.println("Case " + t);
            solve(sc, cp);
        }
        cp.close();
    }

    static void solve(ContestScanner sc, ContestPrinter cp) {
        int[][] pos = new int[4][2];
        int[] judgepos = new int[8];
        for (int i = 0; i < 8; i++) {
            pos[i / 2][i % 2] = sc.nextInt();
            judgepos[i] = pos[i / 2][i % 2];
        }
        if ((Math.abs(pos[0][0] - pos[1][0]) + Math.abs(pos[0][1] - pos[1][1])) % 2 == 1) {
            cp.println(-1);
        } else {
            ArrayList<int[]> ans;
            ans = solve1(pos);
            if (ans != null) {
                // System.err.println(JudgeSingleCase.judgeOne(judgepos, ans.size(), ans));
                cp.println(ans.size());
                for (int[] p : ans) {
                    cp.println(p[0] + " " + p[1]);
                }
                return;
            }
            for (int i = 0; i < 4; i++) {
                int temp = pos[i][0];
                pos[i][0] = pos[i][1];
                pos[i][1] = temp;
            }
            ans = solve1(pos);
            if (ans != null) {
                cp.println(ans.size());
                for (int[] p : ans) {
                    cp.println(p[1] + " " + p[0]);
                }
                return;
            }
            for (int i = 0; i < 4; i++) {
                int temp = pos[i][0];
                pos[i][0] = pos[i][1];
                pos[i][1] = temp;
            }
            ans = makePath(
                    new int[][] { pos[0], { pos[0][0], pos[1][1] }, pos[1] }, 1, null);
            // System.err.println(JudgeSingleCase.judgeOne(judgepos, ans.size(), ans));
            cp.println(ans.size());
            for (int[] p : ans) {
                cp.println(p[0] + " " + p[1]);
            }
            return;
        }
    }

    static ArrayList<int[]> solve1(int[][] pos) {
        ArrayList<Integer> xs = new ArrayList<>();
        ArrayList<Integer> ys = new ArrayList<>();
        for (int i = 0; i < 4; i++) {
            xs.add(pos[i][0]);
            ys.add(pos[i][1]);
        }
        xs.sort(null);
        ys.sort(null);
        int[][] cpos = new int[4][2];
        for (int i = 0; i < 4; i++) {
            cpos[i][0] = xs.indexOf(pos[i][0]);
            cpos[i][1] = ys.indexOf(pos[i][1]);
        }
        if (cpos[0][0] == 0 && cpos[1][0] == 3) {
            return makePath(
                    new int[][] { pos[0], { -110, pos[0][1] }, { -110, -110 }, { 110, -110 }, { 110, pos[1][1] },
                            pos[1] },
                    1, null);
        } else if (cpos[0][0] == 3 && cpos[1][0] == 0) {
            return makePath(
                    new int[][] { pos[1], { -110, pos[1][1] }, { -110, -110 }, { 110, -110 }, { 110, pos[0][1] },
                            pos[0] },
                    1, null);
        } else if (cpos[0][0] == 0 && cpos[1][0] == 1 || cpos[0][0] == 3 && cpos[1][0] == 2) {
            return makePath(
                    new int[][] { pos[0], { pos[0][0], pos[1][1] }, pos[1] }, 1, null);
        } else if (cpos[0][0] == 1 && cpos[1][0] == 0 || cpos[0][0] == 2 && cpos[1][0] == 3) {
            return makePath(
                    new int[][] { pos[0], { pos[1][0], pos[0][1] }, pos[1] }, 1, null);
        }
        int[][] pairs = new int[][] { { 0, 3 }, { 1, 2 } };
        for (int[] p : pairs) {
            if (cpos[p[0]][0] == 0 && cpos[p[1]][0] == 3) {
                return makePath(
                        new int[][] { pos[p[0]], { -110, pos[p[0]][1] }, { -110, -110 }, { 110, -110 },
                                { 110, pos[p[1]][1] }, pos[p[1]], { 190, pos[p[1]][1] }, { 190, 190 }, { -190, 190 } },
                        2, null);
            } else if (cpos[p[0]][0] == 3 && cpos[p[1]][0] == 0) {
                return makePath(
                        new int[][] { { 190, 190 }, { -190, 190 }, { -190, pos[p[1]][1] }, pos[p[1]],
                                { -110, pos[p[1]][1] }, { -110, -110 }, { 110, -110 },
                                { 110, pos[p[0]][1] }, pos[p[0]] },
                        0, null);
            } else if (cpos[p[0]][0] == 0 && cpos[p[1]][0] == 1) {
                return makePath(
                        new int[][] { { -108, -108 }, { 110, -108 }, { 110, -110 }, { -110, -110 },
                                { -110, pos[p[0]][1] }, pos[p[0]],
                                { pos[p[0]][0], pos[p[1]][1] },
                                pos[p[1]] },
                        0, new int[] { pos[p[0]][0] - 1, pos[p[0]][1] + Integer.signum(pos[p[1]][1] - pos[p[0]][1]) });
            } else if (cpos[p[0]][0] == 1 && cpos[p[1]][0] == 0) {
                return makePath(
                        new int[][] { { -108, -108 }, { 110, -108 }, { 110, -110 }, { -110, -110 },
                                { -110, pos[p[1]][1] }, pos[p[1]],
                                { pos[p[1]][0], pos[p[0]][1] },
                                pos[p[0]] },
                        0, new int[] { pos[p[1]][0] - 1, pos[p[1]][1] + Integer.signum(pos[p[0]][1] - pos[p[1]][1]) });
            } else if (cpos[p[0]][0] == 3 && cpos[p[1]][0] == 2) {
                return makePath(
                        new int[][] { { 108, -108 }, { -110, -108 }, { -110, -110 }, { 110, -110 },
                                { 110, pos[p[0]][1] }, pos[p[0]],
                                { pos[p[0]][0], pos[p[1]][1] },
                                pos[p[1]] },
                        0, new int[] { pos[p[0]][0] + 1, pos[p[0]][1] + Integer.signum(pos[p[1]][1] - pos[p[0]][1]) });
            } else if (cpos[p[0]][0] == 2 && cpos[p[1]][0] == 3) {
                return makePath(
                        new int[][] { { 108, -108 }, { -110, -108 }, { -110, -110 }, { 110, -110 },
                                { 110, pos[p[1]][1] }, pos[p[1]],
                                { pos[p[1]][0], pos[p[0]][1] },
                                pos[p[0]] },
                        0, new int[] { pos[p[1]][0] + 1, pos[p[1]][1] + Integer.signum(pos[p[0]][1] - pos[p[1]][1]) });
            }
        }
        return null;
    }

    static ArrayList<int[]> makePath(int[][] path, int hole, int[] avoid) {
        for (int[] p : path) {
            p[0] += 200;
            p[1] += 200;
        }
        int[][] map = new int[401][401];
        ArrayList<int[]> list = new ArrayList<>();
        int[] now = new int[] { path[0][0], path[0][1] };
        for (int[] p : path) {
            while (true) {
                if (now[0] < p[0])
                    now[0]++;
                if (now[0] > p[0])
                    now[0]--;
                if (now[1] < p[1])
                    now[1]++;
                if (now[1] > p[1])
                    now[1]--;
                if (map[now[0]][now[1]] == 0) {
                    map[now[0]][now[1]] = 1;
                    list.add(now.clone());
                }
                if (now[0] == p[0] && now[1] == p[1]) {
                    break;
                }
            }
        }
        for (int i = 1; i < 400; i++) {
            for (int j = 1; j < 400; j++) {
                if (map[i][j] == 0 &&
                        (map[i - 1][j] == 1 || map[i + 1][j] == 1 || map[i][j - 1] == 1 || map[i][j + 1] == 1)) {
                    map[i][j] = 2;
                }
            }
        }
        int[] target;
        if (hole == 0) {
            target = list.get(0);
        } else if (hole == 1) {
            target = list.get(list.size() / 2);
        } else {
            target = list.get(list.size() - 1);
        }
        ArrayList<int[]> cand = new ArrayList<>();
        int[][] dir = { { 1, 0 }, { -1, 0 }, { 0, 1 }, { 0, -1 } };
        for (int[] d : dir) {
            if (map[target[0] + d[0]][target[1] + d[1]] == 2) {
                cand.add(new int[] { target[0] + d[0], target[1] + d[1] });
            }
        }
        for (int[] c : cand) {
            int cnt = 0;
            for (int[] d : dir) {
                if (map[c[0] + d[0]][c[1] + d[1]] == 1) {
                    cnt++;
                }
            }
            if (cnt == 1) {
                map[c[0]][c[1]] = 0;
            }
        }
        if (avoid != null)
            map[avoid[0] + 200][avoid[1] + 200] = 0;
        ArrayList<int[]> res = new ArrayList<>();
        for (int i = 0; i <= 400; i++) {
            for (int j = 0; j <= 400; j++) {
                if (map[i][j] == 2) {
                    res.add(new int[] { i - 200, j - 200 });
                }
            }
        }
        return res;
    }

    static class ContestScanner {
        private final java.io.InputStream in;
        private final byte[] buffer = new byte[1024];
        private int ptr = 0;
        private int buflen = 0;

        private static final long LONG_MAX_TENTHS = 922337203685477580L;
        private static final int LONG_MAX_LAST_DIGIT = 7;
        private static final int LONG_MIN_LAST_DIGIT = 8;

        public ContestScanner(java.io.InputStream in) {
            this.in = in;
        }

        public ContestScanner() {
            this(System.in);
        }

        private boolean hasNextByte() {
            if (ptr < buflen) {
                return true;
            } else {
                ptr = 0;
                try {
                    buflen = in.read(buffer);
                } catch (java.io.IOException e) {
                    e.printStackTrace();
                }
                if (buflen <= 0) {
                    return false;
                }
            }
            return true;
        }

        private int readByte() {
            if (hasNextByte())
                return buffer[ptr++];
            else
                return -1;
        }

        private static boolean isPrintableChar(int c) {
            return 33 <= c && c <= 126;
        }

        public boolean hasNext() {
            while (hasNextByte() && !isPrintableChar(buffer[ptr]))
                ptr++;
            return hasNextByte();
        }

        public String next() {
            if (!hasNext())
                throw new java.util.NoSuchElementException();
            StringBuilder sb = new StringBuilder();
            int b = readByte();
            while (isPrintableChar(b)) {
                sb.appendCodePoint(b);
                b = readByte();
            }
            return sb.toString();
        }

        public long nextLong() {
            if (!hasNext())
                throw new java.util.NoSuchElementException();
            long n = 0;
            boolean minus = false;
            int b = readByte();
            if (b == '-') {
                minus = true;
                b = readByte();
            }
            if (b < '0' || '9' < b) {
                throw new NumberFormatException();
            }
            while (true) {
                if ('0' <= b && b <= '9') {
                    int digit = b - '0';
                    if (n >= LONG_MAX_TENTHS) {
                        if (n == LONG_MAX_TENTHS) {
                            if (minus) {
                                if (digit <= LONG_MIN_LAST_DIGIT) {
                                    n = -n * 10 - digit;
                                    b = readByte();
                                    if (!isPrintableChar(b)) {
                                        return n;
                                    } else if (b < '0' || '9' < b) {
                                        throw new NumberFormatException(
                                                String.format("%d%s... is not number", n, Character.toString(b)));
                                    }
                                }
                            } else {
                                if (digit <= LONG_MAX_LAST_DIGIT) {
                                    n = n * 10 + digit;
                                    b = readByte();
                                    if (!isPrintableChar(b)) {
                                        return n;
                                    } else if (b < '0' || '9' < b) {
                                        throw new NumberFormatException(
                                                String.format("%d%s... is not number", n, Character.toString(b)));
                                    }
                                }
                            }
                        }
                        throw new ArithmeticException(
                                String.format("%s%d%d... overflows long.", minus ? "-" : "", n, digit));
                    }
                    n = n * 10 + digit;
                } else if (b == -1 || !isPrintableChar(b)) {
                    return minus ? -n : n;
                } else {
                    throw new NumberFormatException();
                }
                b = readByte();
            }
        }

        public int nextInt() {
            long nl = nextLong();
            if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
                throw new NumberFormatException();
            return (int) nl;
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public long[] nextLongArray(int length) {
            long[] array = new long[length];
            for (int i = 0; i < length; i++)
                array[i] = this.nextLong();
            return array;
        }

        public long[] nextLongArray(int length, java.util.function.LongUnaryOperator map) {
            long[] array = new long[length];
            for (int i = 0; i < length; i++)
                array[i] = map.applyAsLong(this.nextLong());
            return array;
        }

        public int[] nextIntArray(int length) {
            int[] array = new int[length];
            for (int i = 0; i < length; i++)
                array[i] = this.nextInt();
            return array;
        }

        public int[][] nextIntArrayMulti(int length, int width) {
            int[][] arrays = new int[width][length];
            for (int i = 0; i < length; i++) {
                for (int j = 0; j < width; j++)
                    arrays[j][i] = this.nextInt();
            }
            return arrays;
        }

        public int[] nextIntArray(int length, java.util.function.IntUnaryOperator map) {
            int[] array = new int[length];
            for (int i = 0; i < length; i++)
                array[i] = map.applyAsInt(this.nextInt());
            return array;
        }

        public double[] nextDoubleArray(int length) {
            double[] array = new double[length];
            for (int i = 0; i < length; i++)
                array[i] = this.nextDouble();
            return array;
        }

        public double[] nextDoubleArray(int length, java.util.function.DoubleUnaryOperator map) {
            double[] array = new double[length];
            for (int i = 0; i < length; i++)
                array[i] = map.applyAsDouble(this.nextDouble());
            return array;
        }

        public long[][] nextLongMatrix(int height, int width) {
            long[][] mat = new long[height][width];
            for (int h = 0; h < height; h++)
                for (int w = 0; w < width; w++) {
                    mat[h][w] = this.nextLong();
                }
            return mat;
        }

        public int[][] nextIntMatrix(int height, int width) {
            int[][] mat = new int[height][width];
            for (int h = 0; h < height; h++)
                for (int w = 0; w < width; w++) {
                    mat[h][w] = this.nextInt();
                }
            return mat;
        }

        public double[][] nextDoubleMatrix(int height, int width) {
            double[][] mat = new double[height][width];
            for (int h = 0; h < height; h++)
                for (int w = 0; w < width; w++) {
                    mat[h][w] = this.nextDouble();
                }
            return mat;
        }

        public char[][] nextCharMatrix(int height, int width) {
            char[][] mat = new char[height][width];
            for (int h = 0; h < height; h++) {
                String s = this.next();
                for (int w = 0; w < width; w++) {
                    mat[h][w] = s.charAt(w);
                }
            }
            return mat;
        }
    }

    static class ContestPrinter extends java.io.PrintWriter {
        public ContestPrinter(java.io.PrintStream stream) {
            super(stream);
        }

        public ContestPrinter() {
            super(System.out);
        }

        private static String dtos(double x, int n) {
            StringBuilder sb = new StringBuilder();
            if (x < 0) {
                sb.append('-');
                x = -x;
            }
            x += Math.pow(10, -n) / 2;
            sb.append((long) x);
            sb.append(".");
            x -= (long) x;
            for (int i = 0; i < n; i++) {
                x *= 10;
                sb.append((int) x);
                x -= (int) x;
            }
            return sb.toString();
        }

        @Override
        public void print(float f) {
            super.print(dtos(f, 20));
        }

        @Override
        public void println(float f) {
            super.println(dtos(f, 20));
        }

        @Override
        public void print(double d) {
            super.print(dtos(d, 20));
        }

        @Override
        public void println(double d) {
            super.println(dtos(d, 20));
        }

        public void printArray(int[] array, String separator) {
            int n = array.length;
            for (int i = 0; i < n - 1; i++) {
                super.print(array[i]);
                super.print(separator);
            }
            super.println(array[n - 1]);
        }

        public void printArray(int[] array) {
            this.printArray(array, " ");
        }

        public void printArray(int[] array, String separator, java.util.function.IntUnaryOperator map) {
            int n = array.length;
            for (int i = 0; i < n - 1; i++) {
                super.print(map.applyAsInt(array[i]));
                super.print(separator);
            }
            super.println(map.applyAsInt(array[n - 1]));
        }

        public void printArray(int[] array, java.util.function.IntUnaryOperator map) {
            this.printArray(array, " ", map);
        }

        public void printArray(long[] array, String separator) {
            int n = array.length;
            for (int i = 0; i < n - 1; i++) {
                super.print(array[i]);
                super.print(separator);
            }
            super.println(array[n - 1]);
        }

        public void printArray(long[] array) {
            this.printArray(array, " ");
        }

        public void printArray(long[] array, String separator, java.util.function.LongUnaryOperator map) {
            int n = array.length;
            for (int i = 0; i < n - 1; i++) {
                super.print(map.applyAsLong(array[i]));
                super.print(separator);
            }
            super.println(map.applyAsLong(array[n - 1]));
        }

        public void printArray(long[] array, java.util.function.LongUnaryOperator map) {
            this.printArray(array, " ", map);
        }

    }
}