foo.cc: In function 'int main()':
foo.cc:7:2: error: 'cin' was not declared in this scope
cin >> a >> b;
^~~
foo.cc:7:2: note: suggested alternative:
In file included from foo.cc:2:0:
/usr/include/c++/7/iostream:60:18: note: 'std::cin'
extern istream cin; /// Linked to standard input
^~~
foo.cc:19:2: error: 'cout' was not declared in this scope
cout << ans;
^~~~
foo.cc:19:2: note: suggested alternative:
In file included from foo.cc:2:0:
/usr/include/c++/7/iostream:61:18: note: 'std::cout'
extern ostream cout; /// Linked to standard output
^~~~
自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。