public class Exercise8
{  
  // rotate a by d elements to the left
  public static void rotateLeft(int[] a, int d)
  {
    int n = a.length;
    revert(a, 0, d);
    revert(a, d, n-d);
    revert(a, 0, n);
  }
  
  // revert a[p..p+n-1]
  public static void revert(int[] a, int p, int n)
  {
    int left = p;
    int right = p+n-1;
    while (left < right)
    {
      int t = a[left];
      a[left] = a[right];
      a[right] = t;
      left = left+1;
      right = right-1;
    }
  }
}