View Compilation Error

0_0_35207550_21471.cpp: In function 'bool chk(int, int)':
0_0_35207550_21471.cpp:13:100: error: 'bx' was not declared in this scope
     return x >= 1 && x <= n && y >= 1 && y <= m && !vis[x][y] && (!maze[x][y] || maze[x][y] ==maze[bx][by]);
                                                                                                    ^
0_0_35207550_21471.cpp:13:104: error: 'by' was not declared in this scope
     return x >= 1 && x <= n && y >= 1 && y <= m && !vis[x][y] && (!maze[x][y] || maze[x][y] ==maze[bx][by]);
                                                                                                        ^