foo.c: In function 'main':
foo.c:8:9: error: too few arguments to function 'fgets'
    8 |         fgets(a);
      |         ^~~~~
In file included from foo.c:1:
/nix/store/rffag931pvbdiabwwa539wnwg1piqpx0-glibc-2.35-163-dev/include/stdio.h:592:14: note: declared here
  592 | extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)
      |              ^~~~~
foo.c:9:9: error: too few arguments to function 'fgets'
    9 |         fgets(b);
      |         ^~~~~
In file included from foo.c:1:
/nix/store/rffag931pvbdiabwwa539wnwg1piqpx0-glibc-2.35-163-dev/include/stdio.h:592:14: note: declared here
  592 | extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)
      |              ^~~~~

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