foo.cc: In function 'void dts::dfs(std::vector<double>)':
foo.cc:30:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (ll i=0; i<rec.size(); i++)
                 ~^~~~~~~~~~~
foo.cc:31:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (ll j=i+1; j<rec.size(); j++) {
                    ~^~~~~~~~~~~
foo.cc:32:24: 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:59:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%lf",&a[i]);
    ~~~~~^~~~~~~~~~~~~
foo.cc:62:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lf",&key);
     ~~~~~^~~~~~~~~~~~

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