foo.cc: In function 'void dts::dfs(std::vector<long long int>)':
foo.cc:32:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (ll i=0;i<rec.size();i++)
                ~^~~~~~~~~~~
foo.cc:33:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (ll j=i+1;j<rec.size();j++)
                   ~^~~~~~~~~~~
foo.cc:35:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      for (ll k=0,l=0;k<rec.size();k++)
                      ~^~~~~~~~~~~
foo.cc: In function 'void dts::main()':
foo.cc:68:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%lld",&a[i]);
    ~~~~~^~~~~~~~~~~~~~
foo.cc:72:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld",&key);
     ~~~~~^~~~~~~~~~~~~

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