foo.c: In function 'main':
foo.c:14:5: warning: implicit declaration of function 'output' [-Wimplicit-function-declaration]
   14 |     output(num);
      |     ^~~~~~
foo.c: In function 'output':
foo.c:26:1: error: expected declaration or statement at end of input
   26 | }
      | ^
foo.c:27: warning: control reaches end of non-void function [-Wreturn-type]

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