/in/foo.c: In function 'main':
/in/foo.c:9:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'int *' [-Wformat=]
  scanf("%s%s",u,v);
         ~^    ~
         %ls
/in/foo.c:9:12: warning: format '%s' expects argument of type 'char *', but argument 3 has type 'int *' [-Wformat=]
  scanf("%s%s",u,v);
           ~^    ~
           %ls
/in/foo.c:12:10: warning: passing argument 1 of 'strcat' from incompatible pointer type [-Wincompatible-pointer-types]
   strcat(v,u);
          ^
In file included from /in/foo.c:2:0:
/usr/include/string.h:133:14: note: expected 'char * restrict' but argument is of type 'int *'
 extern char *strcat (char *__restrict __dest, const char *__restrict __src)
              ^~~~~~
/in/foo.c:12:12: warning: passing argument 2 of 'strcat' from incompatible pointer type [-Wincompatible-pointer-types]
   strcat(v,u);
            ^
In file included from /in/foo.c:2:0:
/usr/include/string.h:133:14: note: expected 'const char * restrict' but argument is of type 'int *'
 extern char *strcat (char *__restrict __dest, const char *__restrict __src)
              ^~~~~~
/in/foo.c:13:10: warning: passing argument 1 of 'strcat' from incompatible pointer type [-Wincompatible-pointer-types]
   strcat(u,v);
          ^
In file included from /in/foo.c:2:0:
/usr/include/string.h:133:14: note: expected 'char * restrict' but argument is of type 'int *'
 extern char *strcat (char *__restrict __dest, const char *__restrict __src)
              ^~~~~~
/in/foo.c:13:12: warning: passing argument 2 of 'strcat' from incompatible pointer type [-Wincompatible-pointer-types]
   strcat(u,v);
            ^
In file included from /in/foo.c:2:0:
/usr/include/string.h:133:14: note: expected 'const char * restrict' but argument is of type 'int *'
 extern char *strcat (char *__restrict __dest, const char *__restrict __src)
              ^~~~~~
/in/foo.c:16:11: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'int *' [-Wformat=]
  printf("%s",u);
          ~^  ~
          %ls