Problem in array partition program

#include<stdio.h>
#include<conio.h>
int partition(int [],int,int);
main()
{
    int n,i;
    printf("enter the number of elements in the array\n");
    scanf("%d",&n);
    int a[n];
    for(i=0;i<n;i++)
    {
        printf("enter the number\n");
        scanf("%d",a+i);
    }
    printf("the index of the pivot is %d and the partitioned array is\n",partition(a,0,n-1));
    for(i=0;i<n;i++) printf("%d\t",*(a+i));
    getch();
}
int partition(int a[],int lower,int upper)
{
    int p=a[lower];
    int i=lower,j=upper+1,temp;
    do
       { do{i++;}while(a[i]>=p);
         do{j--;}while(a[j]<=p);
         if(i<j){ temp=a[i];
                  a[i]=a[j];
                  a[j]=temp;
                }
       }while(i>=j);

      a[lower]=a[j];
      a[j]=p;
      return j;
}