foo.cc: In function 'int bfs_1(int)':
foo.cc:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i=1;i<a[now].size();i++)
                      ~^~~~~~~~~~~~~~
foo.cc:32:16: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
             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]
             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]
             scanf("%d",&d);
             ~~~~~^~~~~~~~~

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