foo.cc: In function 'int main()':
foo.cc:9:6: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
  if(a>b>c||a>c>b) x=a;
     ~^~
foo.cc:9:13: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
  if(a>b>c||a>c>b) x=a;
            ~^~
foo.cc:11:7: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
   if(b>a>c||b>c>a) x=b;
      ~^~
foo.cc:11:14: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
   if(b>a>c||b>c>a) x=b;
             ~^~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。