foo.cc:1:1: error: 'include' does not name a type; did you mean '__has_include'?
 include <iostream>
 ^~~~~~~
 __has_include
foo.cc: In function 'int main()':
foo.cc:9:2: error: 'cin' was not declared in this scope
  cin >> a;
  ^~~
foo.cc:9:2: note: suggested alternative: 'main'
  cin >> a;
  ^~~
  main
foo.cc:11:2: error: 'cout' was not declared in this scope
  cout << n;
  ^~~~

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