/in/foo.cc: In function 'int get(char*, int)':
/in/foo.cc:50:9: warning: unused variable 'j' [-Wunused-variable]
   int i,j,k,len=strlen(s);
         ^
/in/foo.cc:50:11: warning: unused variable 'k' [-Wunused-variable]
   int i,j,k,len=strlen(s);
           ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:99:9: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
   gets(a);
         ^
In file included from /usr/include/c++/7/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:105:13: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
       gets(b);
             ^
In file included from /usr/include/c++/7/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:98:11: warning: unused variable 'k' [-Wunused-variable]
   int i,j,k,n;
           ^
/tmp/cc4kHVTN.o: In function `main':
foo.cc:(.text.startup+0x5c): warning: the `gets' function is dangerous and should not be used.