add pointer size

a3-1/sizes.c

@@ -18,6 +18,8 @@ int main(void) {
     printf("\n");
     printf("double: %ld\n", sizeof(d));
     printf("long: %ld\n", sizeof(ld));
+    printf("\n");
+    printf("pointer: %ld\n", sizeof(&i));
 
     return 0;
 }