/in/foo.c: In function 'main':
/in/foo.c:7:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(a);
  ^~~~
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c:12:15: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(a[i]>='A'&&a[i]<='A'+25-k||a[i]>='a'&&a[i]<='a'+25-k)
      ~~~~~~~~~^~~~~~~~~~~~~~~~
/in/foo.c:14:25: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   else if(a[i]>='A'+26-k&&a[i]<='Z'||a[i]>='a'+26-k&&a[i]<='z'+26-k)
           ~~~~~~~~~~~~~~^~~~~~~~~~~
/tmp/ccuACagk.o: In function `main':
foo.c:(.text.startup+0x12): warning: the `gets' function is dangerous and should not be used.