View Compilation Error

0_0_20514680_28375.cpp: In function 'void dfs(int, int)':
0_0_20514680_28375.cpp:29:25: error: 'n' was not declared in this scope
  if (x<0 || y<0 || x >= n || y >= m) return;
                         ^
0_0_20514680_28375.cpp:29:35: error: 'm' was not declared in this scope
  if (x<0 || y<0 || x >= n || y >= m) return;
                                   ^