foo.c: In function 'main':
foo.c:11:17: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'int *' [-Wformat=]
         scanf("%s",a[b[j]]);
                ~^  ~
                %ls
foo.c:14:18: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'int *' [-Wformat=]
         printf("%s\n",a[j]);
                 ~^    ~
                 %ls
foo.c:5:15: warning: unused variable 'k' [-Wunused-variable]
     int i=0,j,k;
               ^
foo.c:8:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d",&b[i++]);
         ^~~~~~~~~~~~~~~~~~~
foo.c:11:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%s",a[b[j]]);
         ^~~~~~~~~~~~~~~~~~~