foo.cc: In function 'int dfs(int, int)':
foo.cc:22:1: warning: no return statement in function returning non-void [-Wreturn-type]
   22 | }
      | ^
foo.cc: In function 'int main()':
foo.cc:25:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   25 |  scanf("%d%d", &m, &n);
      |  ~~~~~^~~~~~~~~~~~~~~~
foo.cc:31:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   31 |    scanf("%d", &a[i][j]);
      |    ~~~~~^~~~~~~~~~~~~~~~
foo.cc:40:5: warning: 'sy' may be used uninitialized in this function [-Wmaybe-uninitialized]
   40 |  dfs(sx,sy);
      |  ~~~^~~~~~~
foo.cc:40:5: warning: 'sx' may be used uninitialized in this function [-Wmaybe-uninitialized]

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