/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:9:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for(i=j=0;a[i]!='\0';i++)
  ^~~
/in/foo.c:12:3: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
   b[j]='\0';
   ^
/tmp/ccO2wOnd.o: In function `main':
foo.c:(.text.startup+0xc): warning: the `gets' function is dangerous and should not be used.