foo.c:11:12: error: unknown type name 'highnum'
 int readin(highnum *p,char s[])
            ^~~~~~~
foo.c:24:15: error: unknown type name 'highnum'
 int countfive(highnum *p,char s[])
               ^~~~~~~
foo.c: In function 'main':
foo.c:51:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(s);
  ^~~~
In file included from /usr/include/stdio.h:862:0,
                 from foo.c:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:232:1: note: declared here
 gets (char *__str)
 ^~~~
foo.c:52:2: error: unknown type name 'highnum'; use 'struct' keyword to refer to the type
  highnum x;
  ^~~~~~~
  struct 
foo.c:53:3: error: request for member 'n' in something not a structure or union
  x.n=readin(&x,s);
   ^
foo.c:53:6: warning: implicit declaration of function 'readin'; did you mean 'main'? [-Wimplicit-function-declaration]
  x.n=readin(&x,s);
      ^~~~~~
      main
foo.c:54:6: warning: implicit declaration of function 'countfive' [-Wimplicit-function-declaration]
  cnt=countfive(&x,s);
      ^~~~~~~~~
foo.c:51:2: warning: ignoring return value of 'gets', declared with attribute warn_unused_result [-Wunused-result]
  gets(s);
  ^~~~~~~

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