foo.cc:4:7: error: expected nested-name-specifier before 'namepace'
 using namepace std;
       ^~~~~~~~
foo.cc: In function 'int main()':
foo.cc:10:2: error: 'cin' was not declared in this scope
  cin >> n >> m;
  ^~~
foo.cc:10:2: note: suggested alternative:
In file included from foo.cc:1:0:
/usr/include/c++/7/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^~~
foo.cc:11:2: error: 'c' was not declared in this scope
  c = m * 0.8;
  ^

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