/in/foo.c: In function 'main':
/in/foo.c:23:15: warning: passing argument 2 of 'fgets' makes integer from pointer without a cast [-Wint-conversion]
     fgets(s1, stdin);
               ^~~~~
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:624:14: note: expected 'int' but argument is of type 'struct _IO_FILE *'
 extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)
              ^~~~~
/in/foo.c:23:5: error: too few arguments to function 'fgets'
     fgets(s1, stdin);
     ^~~~~
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:624:14: note: declared here
 extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)
              ^~~~~
/in/foo.c:28:15: warning: passing argument 2 of 'fgets' makes integer from pointer without a cast [-Wint-conversion]
     fgets(s2, stdin);
               ^~~~~
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:624:14: note: expected 'int' but argument is of type 'struct _IO_FILE *'
 extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)
              ^~~~~
/in/foo.c:28:5: error: too few arguments to function 'fgets'
     fgets(s2, stdin);
     ^~~~~
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:624:14: note: declared here
 extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)
              ^~~~~