foo.cc: In function 'void tarjan(int, int)':
foo.cc:19:6: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   19 |    if(to!=fa)
      |      ^
foo.cc: In function 'int main()':
foo.cc:33:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   33 |   scanf("%d%d",&n,&m);
      |   ~~~~~^~~~~~~~~~~~~~
foo.cc:35:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   35 |    scanf("%d%d",&a,&b);
      |    ~~~~~^~~~~~~~~~~~~~

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