#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

void change_by_ptr(int* a, int b);
void change_by_double_ptr(int **a, int b);

int main(void)
{
    int a,b,c;
    int* a_ptr;
    int** double_ptr;
    a_ptr = &a;
    double_ptr = &a_ptr;

    scanf("%d", &a);
    printf("change a to ..");
    scanf("%d", &b);
    change_by_ptr(a_ptr, b);
    printf("now a is %d\n", a);
    prinft("change a to ..");
    scanf("%d", &c);
    change_by_double_ptr(double_ptr, c);
    printf("now a is %d\n", a);
    return 0;
}

void change_by_ptr(int* n1, int n2)
{
    *n1 = n2;
}

int change_by_double_ptr(int** n1, int n2)
{
    *n1 = n2;
}