/in/foo.cc: In function 'int main()':
/in/foo.cc:31:5: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(s1);
     ^~~~
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:31:12: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(s1);
            ^
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:32:5: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(s2);
     ^~~~
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:32:12: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(s2);
            ^
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:33:30: error: too few arguments to function 'void Concat(char*, char*)'
     printf("%d %d", Concat(s1), Concat(s2));
                              ^
/in/foo.cc:18:6: note: declared here
 void Concat(char s1[],char s2[])
      ^~~~~~
/in/foo.cc:33:42: error: too few arguments to function 'void Concat(char*, char*)'
     printf("%d %d", Concat(s1), Concat(s2));
                                          ^
/in/foo.cc:18:6: note: declared here
 void Concat(char s1[],char s2[])
      ^~~~~~