foo.c: In function 'main':
foo.c:6:2: error: 'cin' undeclared (first use in this function); did you mean 'main'?
  cin>>a>>b;
  ^~~
  main
foo.c:6:2: note: each undeclared identifier is reported only once for each function it appears in
foo.c:7:2: error: 'cout' undeclared (first use in this function)
  cout<<a+b;
  ^~~~

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