View Compilation Error

0_0_29910268_16054.cpp: In function 'void dfs(int, int)':
0_0_29910268_16054.cpp:25:13: error: 'n' was not declared in this scope
  if(l<=0||l>n||r<=0||r>=m) return ; 
             ^
0_0_29910268_16054.cpp:25:25: error: 'm' was not declared in this scope
  if(l<=0||l>n||r<=0||r>=m) return ; 
                         ^