/in/foo.cc: In function 'int main()':
/in/foo.cc:65:5: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(lu);
     ^~~~
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:65:12: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(lu);
            ^
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:68:14: warning: the address of 'size_t strlen(const char*)' will never be NULL [-Waddress]
     if(strlen==0)
        ~~~~~~^~~
/in/foo.cc: In function 'bool check(char)':
/in/foo.cc:44:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/tmp/cciCxjip.o: In function `main':
foo.cc:(.text.startup+0x110): warning: the `gets' function is dangerous and should not be used.