/in/foo.c:2:19: warning: extra tokens at end of #include directive
 #include<string.h>;
                   ^
/in/foo.c: In function 'main':
/in/foo.c:10:1: 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:24:5: warning: unused variable 'f' [-Wunused-variable]
 int f=0;
     ^
/in/foo.c:6:13: warning: unused variable 'k' [-Wunused-variable]
 int i=0,j=0,k=0,num;
             ^
/tmp/cc6FYtqF.o: In function `main':
foo.c:(.text.startup+0x1c): warning: the `gets' function is dangerous and should not be used.