Mã chấm: 269565

Main.cc: In function ‘int main()’:
Main.cc:7:11: error: expected nested-name-specifier before ‘System’
     using System;
           ^~~~~~
Main.cc:8:7: error: expected nested-name-specifier before ‘System’
 using System.Linq;
       ^~~~~~
Main.cc:9:7: error: expected nested-name-specifier before ‘System’
 using System.Collections.Generic;
       ^~~~~~
Main.cc:17:2: error: expected ‘;’ after class definition
 }
  ^
  ;