#include <stdio.h>

int main() {
    int a=10;
    int *ptr;
    ptr=&a;
    printf("value of ptr:%d\n",a);
    *ptr=20;
    printf("new value of a:%d\n",a);
    int *p,arr;
    *p=arr;
    for(int i=0;i<3;i++){
        printf("arithmetic:%d\n",i,*(p+i));
    }
    p++;
    printf("value of arr[0]:%d\n",*p);
    
}