foo.cc: In function 'int main()':
foo.cc:21:30: error: expression cannot be used as a function
   21 |                 up*=(LL)(n-e)(e+1)*k;
      |                         ~~~~~^~~~~
foo.cc:21:36: error: 'k' was not declared in this scope
   21 |                 up*=(LL)(n-e)(e+1)*k;
      |                                    ^
foo.cc:22:23: error: 'N' was not declared in this scope
   22 |                 down*=N*N;
      |                       ^

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