foo.cc: In function 'int bfs_1(int)':
foo.cc:31:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |         for (int i=1;i<a[now].size();i++)
      |                      ~^~~~~~~~~~~~~~
foo.cc:32:16: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   32 |             if (del[a[now][i]]==0)
      |                ^
foo.cc: In function 'int main()':
foo.cc:60:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   60 |             scanf("%d%d",&x,&y);
      |             ~~~~~^~~~~~~~~~~~~~
foo.cc:67:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   67 |             scanf("%d",&d);
      |             ~~~~~^~~~~~~~~

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