foo.c: In function 'Merge':
foo.c:47:30: error: 'na' undeclared (first use in this function); did you mean 'n2'?
   47 |         for (int i = 0; i < (na + nb); i++)
      |                              ^~
      |                              n2
foo.c:47:30: note: each undeclared identifier is reported only once for each function it appears in
foo.c:47:35: error: 'nb' undeclared (first use in this function); did you mean 'n2'?
   47 |         for (int i = 0; i < (na + nb); i++)
      |                                   ^~
      |                                   n2

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