output_description: Print a $8 \times 8$ chess board by strings where a square with a queen is
  represented by 'Q' and an empty square is represented by '.'.
input_description: In the first line, an integer $k$ is given. In the following $k$ lines, each
  square where a queen is already placed is given by two integers $r$ and $c$.
  $r$ and $c$ respectively denotes the row number and the column number. The
  row/column numbers start with 0.
attempt: import copy
  
  n = int(input())
  
  dotsa = []
  for _ in range(n):
      y, x = map(int, input().split(" "))
      dotsa.append([y, x])
  
  pattern = []
  pattern.append(dotsa)
  
  
  for y in range(8):
      nextpattern = []
      # print("#######")
      # print(pattern)
      for pat in pattern:
          # print(";;;;;;;;;;;;;;;;;;;;;")
          # print(pat)
          flag = False
          for dot in pat:
              if dot[0] == y:
                  flag = True
                  break
  
          if flag:
              nextpattern = pattern
              continue
  
          ifFound = False
          for x in range(8):
              ank = len(pat)
              flag2 = True
              for i in range(ank):
                  if abs(pat[i][0] - y) == abs(pat[i][1] - x) or pat[i][1] == x:
                      flag2 = False
                      break
              if flag2:
                  # print("appended")
                  # print(y)
                  # print(x)
                  tmp = copy.deepcopy(pat)
                  tmp.append([y, x])
                  nextpattern.append(tmp)
          # print("x loop end")
      pattern = nextpattern
  
  ans = pattern[0]
  board = [["."] * 8 for i in range(8)]
  # print(ans)
  for ele in ans:
      board[ele[1]][ele[0]] = "Q"
  for row in board:
      print("".join(map(str, row)))
  
problem_description: 8 Queens Problem
  
  The goal of 8 Queens Problem is to put eight queens on a chess-board such that
  none of them threatens any of others. A queen threatens the squares in the
  same row, in the same column, or on the same diagonals as shown in the
  following figure.
  
  ![](https://judgeapi.u-aizu.ac.jp/resources/images/IMAGE2_ALDS1_13_A_8queens)  
  
  For a given chess board where $k$ queens are already placed, find the solution
  of the 8 queens problem.
samples: [{"input": "2\n    2 2\n    5 3", "output": "......Q.\n    Q.......\n    ..Q.....\n    .......Q\n    .....Q..\n    ...Q....\n    .Q......\n    ....Q..."}]