/in/foo.c: In function 'main':
/in/foo.c:8:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'char (*)[100000]' [-Wformat=]
  scanf("%s", &sa);
         ~^   ~~~
/in/foo.c:9:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'char (*)[100000]' [-Wformat=]
  scanf("%s", &sb);
         ~^   ~~~
/in/foo.c:12:3: warning: implicit declaration of function 'strcat' [-Wimplicit-function-declaration]
   strcat(sb, sa);
   ^~~~~~
/in/foo.c:12:3: warning: incompatible implicit declaration of built-in function 'strcat'
/in/foo.c:12:3: note: include '<string.h>' or provide a declaration of 'strcat'
/in/foo.c:5:6: warning: unused variable 'x' [-Wunused-variable]
  int x, n;
      ^