foo.c: In function 'main':
foo.c:6:2: error: 'cout' undeclared (first use in this function)
  cout<<x+y<<endl;
  ^~~~
foo.c:6:2: note: each undeclared identifier is reported only once for each function it appears in
foo.c:6:13: error: 'endl' undeclared (first use in this function)
  cout<<x+y<<endl;
             ^~~~

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