Error Output

std::cerr works like std::cout
It is used for error messages
std::cerr will be ignored for marking
So debugging output should go to std::cerr
  #include  <iostream>
  int  main()  {
     std::cerr  <<  "Sent  to  std::cerr\n";
     std::cout  <<  "Sent  to  std::cout\n";
  }