/in/foo.cc:3:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main()
      ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:8:5: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(a);
     ^~~~
In file included from /in/foo.cc:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:8:11: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(a);
           ^
In file included from /in/foo.cc:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:9:5: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(b);
     ^~~~
In file included from /in/foo.cc:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:9:11: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(b);
           ^
In file included from /in/foo.cc:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/tmp/ccnPaoaq.o: In function `main':
foo.cc:(.text.startup+0x12): warning: the `gets' function is dangerous and should not be used.