description: You have an axis-aligned rectangle room with width W and height H, so the lower left corner is in point (0, 0) and the upper right corner is in (W, H).
  
  There is a rectangular table standing in this room. The sides of the table are parallel to the walls, the lower left corner is in (x_1, y_1), and the upper right corner in (x_2, y_2).
  
  You want to place another rectangular table in this room with width w and height h with the width of the table parallel to the width of the room.
  
  The problem is that sometimes there is not enough space to place the second table without intersecting with the first one (there are no problems with tables touching, though).
  
  You can't rotate any of the tables, but you can move the first table inside the room. 
  
  <image> Example of how you may move the first table.
  
  What is the minimum distance you should move the first table to free enough space for the second one?
  
  Input
  
  The first line contains the single integer t (1 ≤ t ≤ 5000) — the number of the test cases.
  
  The first line of each test case contains two integers W and H (1 ≤ W, H ≤ 10^8) — the width and the height of the room.
  
  The second line contains four integers x_1, y_1, x_2 and y_2 (0 ≤ x_1 < x_2 ≤ W; 0 ≤ y_1 < y_2 ≤ H) — the coordinates of the corners of the first table.
  
  The third line contains two integers w and h (1 ≤ w ≤ W; 1 ≤ h ≤ H) — the width and the height of the second table.
  
  Output
  
  For each test case, print the minimum distance you should move the first table, or -1 if there is no way to free enough space for the second table.
  
  Your answer will be considered correct if its absolute or relative error doesn't exceed 10^{-6}.
  
  Example
  
  Input
  
  
  5
  8 5
  2 1 7 4
  4 2
  5 4
  2 2 5 4
  3 3
  1 8
  0 3 1 6
  1 5
  8 1
  3 0 6 1
  5 1
  8 10
  4 5 7 8
  8 5
  
  
  Output
  
  
  1.000000000
  -1
  2.000000000
  2.000000000
  0.000000000
  
  Note
  
  The configuration of the first test case is shown in the picture. But the movement of the first table is not optimal. One of the optimal movement, for example, is to move the table by (0, -1), so the lower left corner will move from (2, 1) to (2, 0). Then you can place the second table at (0, 3)-(4, 5).
  
  In the second test case, there is no way to fit both tables in the room without intersecting.
  
  In the third test case, you can move the first table by (0, 2), so the lower left corner will move from (0, 3) to (0, 5).
solution: import java.net.Inet4Address;
  import java.util.*;
  import java.io.*;
  
  public class Div735 {
      ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  ////////                                                                                                               /////////
  ////////                                                                                                               /////////
  ////////   HHHH        HHHH  EEEEEEEEEEEEE   MMMM          MMMM         OOOOOO             SSSSSSS      EEEEEEEEEEEEE  /////////
  ////////   HHHH        HHHH  EEEEEEEEEEEEE   MMMMMM      MMMMMM      OOO      OOO        SSSS   SSS     EEEEEEEEEEEEE  /////////
  ////////   HHHH        HHHH  EEEEE           MMMM MMM  MMM MMMM    OOO          OOO    SSSS       SSS   EEEEE          /////////
  ////////   HHHH        HHHH  EEEEE           MMMM  MMMMMM  MMMM   OOO            OOO   SSSS             EEEEE          /////////
  ////////   HHHH        HHHH  EEEEE           MMMM          MMMM  OOO              OOO   SSSSSSS         EEEEE          /////////
  ////////   HHHHHHHHHHHHHHHH  EEEEEEEEEEE     MMMM          MMMM  OOO              OOO      SSSSSS       EEEEEEEEEEE    /////////
  ////////   HHHHHHHHHHHHHHHH  EEEEEEEEEEE     MMMM          MMMM  OOO              OOO         SSSSSSS   EEEEEEEEEEE    /////////
  ////////   HHHH        HHHH  EEEEE           MMMM          MMMM   OOO            OOO              SSSS  EEEEE          /////////
  ////////   HHHH        HHHH  EEEEE           MMMM          MMMM    OOO          OOO     SSS       SSSS  EEEEE          /////////
  ////////   HHHH        HHHH  EEEEEEEEEEEEE   MMMM          MMMM      OOO      OOO        SSS    SSSS    EEEEEEEEEEEEE  /////////
  ////////   HHHH        HHHH  EEEEEEEEEEEEE   MMMM          MMMM         OOOOOO             SSSSSSS      EEEEEEEEEEEEE  /////////
  ////////                                                                                                               /////////
  ////////                                                                                                               /////////
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
      static double dis(int[] a, int[] b) {
          double dx = a[0] - b[0];
          double dy = a[1] - b[1];
          return Math.sqrt(dx * dx + dy * dy);
      }
  
      static boolean inside(int[] p, int[] s, int[] e) {
          boolean is = true;
          is &= (p[0] > s[0] && p[0] < e[0]);
          is &= (p[1] > s[1] && p[1] < e[1]);
  
          return is;
      }
  
      public static void main(String[] args) throws IOException {
          Scanner sc = new Scanner(System.in);
          PrintWriter pw = new PrintWriter(System.out);
          int t = sc.nextInt();
          while (t-- > 0) {
              int W = sc.nextInt();
              int H = sc.nextInt();
              int[] s = sc.nextIntArr(2);
              int[] e = sc.nextIntArr(2);
              int[] need = sc.nextIntArr(2);
              int[] d2 = new int[]{e[0] - s[0], e[1] - s[1]};
              double ans = 1e18;
              if (d2[0] + need[0] <= W) {
                  if (s[0] >= need[0])
                      ans = 0;
                  else ans = Math.min(ans, need[0] - s[0]);
  
                  if (W - e[0] >= need[0])
                      ans = 0;
                  else ans = Math.min(ans, need[0] - (W - e[0]));
              }
              if (d2[1] + need[1] <= H) {
                  if (s[1] >= need[1])
                      ans = 0;
                  else ans = Math.min(ans, need[1] - s[1]);
  
                  if (H - e[1] >= need[1])
                      ans = 0;
                  else ans = Math.min(ans, need[1] - (H - e[1]));
              }
  
              pw.println(ans==1e18?-1:ans);
          }
          pw.flush();
      }
  
      static class Scanner {
          StringTokenizer st;
          BufferedReader br;
  
          public Scanner(FileReader r) {
              br = new BufferedReader(r);
          }
  
          public Scanner(InputStream s) {
              br = new BufferedReader(new InputStreamReader(s));
          }
  
          public String next() throws IOException {
              while (st == null || !st.hasMoreTokens())
                  st = new StringTokenizer(br.readLine());
              return st.nextToken();
          }
  
          public int[] nextIntArr(int n) throws IOException {
              int[] a = new int[n];
              for (int i = 0; i < n; i++) {
                  a[i] = nextInt();
              }
              return a;
          }
  
          public int nextInt() throws IOException {
              return Integer.parseInt(next());
          }
  
          public long nextLong() throws IOException {
              return Long.parseLong(next());
          }
  
          public String nextLine() throws IOException {
              return br.readLine();
          }
  
          public double nextDouble() throws IOException {
              String x = next();
              StringBuilder sb = new StringBuilder("0");
              double res = 0, f = 1;
              boolean dec = false, neg = false;
              int start = 0;
              if (x.charAt(0) == '-') {
                  neg = true;
                  start++;
              }
              for (int i = start; i < x.length(); i++)
                  if (x.charAt(i) == '.') {
                      res = Long.parseLong(sb.toString());
                      sb = new StringBuilder("0");
                      dec = true;
                  } else {
                      sb.append(x.charAt(i));
                      if (dec)
                          f *= 10;
                  }
              res += Long.parseLong(sb.toString()) / f;
              return res * (neg ? -1 : 1);
          }
  
          public boolean ready() throws IOException {
              return br.ready();
          }
      }
  
  }