foo.c: In function 'main':
foo.c:23:23: error: 'cnt' undeclared (first use in this function); did you mean 'int'?
   23 |         printf("%d\n",cnt);
      |                       ^~~
      |                       int
foo.c:23:23: note: each undeclared identifier is reported only once for each function it appears in
foo.c: In function 'one':
foo.c:16:1: warning: control reaches end of non-void function [-Wreturn-type]
   16 | }
      | ^

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