foo.cc: In function 'int main()':
foo.cc:7:2: error: 'cout' was not declared in this scope
  cout<<fixed<<setprecision(2);
  ^~~~
foo.cc:8:2: error: 'cin' was not declared in this scope
  cin>>danjia;
  ^~~

自豪的采用jd5进行评测(github.com/masnn/jd5)