View Compilation Error

0_0_39513233_5565.cpp: In function 'int main()':
0_0_39513233_5565.cpp:16:31: error: 'cs' was not declared in this scope; did you mean 'cos'?
   16 |         cout << "Case " << (++cs) << ": " << (ans & 1 ? "odd" : "even") << '\n';
      |                               ^~
      |                               cos