Please fix error in this code. This code is from sorting algorithm, heapify topic , wriiten in c.i tried so many things but still not able to fix the errors.

#include <stdio.h>
#include <stdlib.h>

#define MAX 20

void BuildHeap(int[], int);
void heapify(int[], int, int);
void swap(int *, int *);

void swap(int *x, int *y)
{

    int temp = *x;
    *x = *y;
    *y = temp;
}
int main()
{

        
    int n, i;
    printf("Enter Array Size\n");
    scanf("%d", &n);

    int arr[n];
    printf("Enter Array Elements\n");
    for (i = 0; i < n; i++)
        scanf("%d", arr[i]);

    BuildHeap(arr, n);

    printf("Sorted array is given in the following way \n");
    for (i = 0; i < n; i++)
        printf("%d", arr[i]);
    printf("\n");
}
void BuildHeap(int arr[], int size)
{
    int i;
    for (i = size / 2; i >= 0; i--)
        heapify(arr, i, size);
}

void heapify(int arr[], int index, int size)
{
    int left = 2 * index + 1;
    int right = left + 1;
    int max = index;

    if (left <= size && arr[left] > arr[max])

        max = left;

    if (right <= size && arr[right] > arr[max])

        max = right;

    if (index != max)
    {
        swap(&arr[max], &arr[index]);
        heapify(arr, max, size);
    }
}