/in/foo.c: In function 'main':
/in/foo.c:5:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(str);
  ^~~~
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:10:12: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(ch>='a'&&ch<=('z'-k)||(ch>='A'&&ch<=('Z'-k)))
     ~~~~~~~^~~~~~~~~~~~~
/in/foo.c:4:22: warning: unused variable 'c' [-Wunused-variable]
  char str[100000],ch,c;
                      ^
/tmp/ccXG5eZV.o: In function `main':
foo.c:(.text.startup+0x1b): warning: the `gets' function is dangerous and should not be used.