foo.c: In function 'one':
foo.c:8:17: error: 'cnt' undeclared (first use in this function); did you mean 'int'?
    8 |                 cnt++;
      |                 ^~~
      |                 int
foo.c:8:17: note: each undeclared identifier is reported only once for each function it appears in
foo.c:16:1: warning: control reaches end of non-void function [-Wreturn-type]
   16 | }
      | ^

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