/in/foo.c: In function 'main':
/in/foo.c:22:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(s1); gets(s2);
  ^~~~
In file included from /in/foo.c:13:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c:22:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(s1); gets(s2);
  ^~~~
In file included from /in/foo.c:13:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c: In function 'change':
/in/foo.c:30:12: warning: 'n' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int temp, n, i, j;
            ^
/tmp/ccJpTOmC.o: In function `main':
foo.c:(.text.startup+0x1c): warning: the `gets' function is dangerous and should not be used.