public bool Add(ref CNode1 p, int x)
{
if (p == null)
{
p = new CNode1(x);
return true;
}
else
if (x == p.value) return false;
else
if (x < p.value) return p.Add(ref p.left, x);
else return p.Add(ref p.right, x);
}
public CNode1(int x)
{
value = x;
left = right = null;
isEdgeMarked = false;
}