foo.cc: In function 'void dfs(int)':
foo.cc:19:30: warning: format '%d' expects argument of type 'int', but argument 2 has type 'int*' [-Wformat=]
             printf("%d",&a[i]);
                         ~~~~~^
foo.cc: In function 'int main()':
foo.cc:32:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&r);
  ~~~~~^~~~~~~~~~~~~~

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