foo.cc: In function 'void Work()':
foo.cc:58:5: error: 'cin' was not declared in this scope
     cin >> o_pos >> K;
     ^~~
foo.cc:58:5: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:75:0,
                 from foo.cc:1:
/usr/include/c++/7/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^~~
foo.cc:62:9: error: 'cout' was not declared in this scope
         cout << last_ans = o_pos;
         ^~~~
foo.cc:62:9: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:75:0,
                 from foo.cc:1:
/usr/include/c++/7/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^~~~
foo.cc:65:9: error: 'cout' was not declared in this scope
         cout << last_ans = 0;
         ^~~~
foo.cc:65:9: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:75:0,
                 from foo.cc:1:
/usr/include/c++/7/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^~~~
foo.cc:74:5: error: 'cout' was not declared in this scope
     cout << last_ans << '\n';
     ^~~~
foo.cc:74:5: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:75:0,
                 from foo.cc:1:
/usr/include/c++/7/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^~~~
foo.cc: In function 'int main()':
foo.cc:78:5: error: 'ios' has not been declared
     ios::sync_with_stdio(0);
     ^~~
foo.cc:79:5: error: 'cin' was not declared in this scope
     cin.tie(0);
     ^~~
foo.cc:79:5: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:75:0,
                 from foo.cc:1:
/usr/include/c++/7/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^~~
foo.cc:80:5: error: 'cout' was not declared in this scope
     cout.tie(0);
     ^~~~
foo.cc:80:5: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:75:0,
                 from foo.cc:1:
/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。