foo.cc:2:7: error: expected nested-name-specifier before ‘namepace’
    2 | using namepace std;
      |       ^~~~~~~~
foo.cc: In function ‘int main()’:
foo.cc:7:9: error: ‘cin’ was not declared in this scope; did you mean ‘std::cin’?
    7 |         cin>>vip;
      |         ^~~
      |         std::cin
In file included from stdc++.h:146:
/nix/gcc-14.2.1.20250322/include/c++/14.2.1.20250322/iostream:62:18: note: ‘std::cin’ declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
foo.cc:11:22: error: ‘P’ was not declared in this scope
   11 |                 case P:jg=jg*0.7;break;
      |                      ^
foo.cc:12:22: error: ‘G’ was not declared in this scope
   12 |                 case G:jg=jg*0.8;break;
      |                      ^
foo.cc:13:22: error: ‘S’ was not declared in this scope
   13 |                 case S:jg=jg*0.9;break;
      |                      ^
foo.cc:16:9: error: ‘cout’ was not declared in this scope; did you mean ‘std::cout’?
   16 |         cout<<jg;
      |         ^~~~
      |         std::cout
/nix/gcc-14.2.1.20250322/include/c++/14.2.1.20250322/iostream:63:18: note: ‘std::cout’ declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~