static void Main(String[] args) {
string[] strs;
strs = Console.ReadLine().Split(' ');
var n = int.Parse(strs[0]);
var t = int.Parse(strs[1]);
var children = new List<int>[n + 1];
var hasParent = new bool[n + 1];
for (var i = 1; i < n; ++i)
{
strs = Console.ReadLine().Split(' ');
var parent = int.Parse(strs[0]);
var child = int.Parse(strs[1]);
if (children[parent] == null)
{
children[parent] = new List<int>();
}
children[parent].Add(child);
hasParent[child] = true;
}
int root = 0;
for (var i = 1; i <= n; ++i)
{
if (!hasParent[i])
{
root = i;
break;
}
}
long result = 0;
var visitedNodes = new CountTree(1, n);
visitedNodes.Add(root);
var stack = new Stack<StackElement>();
stack.Push(new StackElement { Lable = root, CurrentChildIndex = 0 });
while (stack.Count > 0)
{
var node = stack.Peek();
var childrenCount = children[node.Lable] == null ? 0 : children[node.Lable].Count;
if (node.CurrentChildIndex >= childrenCount)
{
visitedNodes.Remove(node.Lable);
stack.Pop();
}
else
{
var nextNode = children[node.Lable][node.CurrentChildIndex];
var lower = nextNode - t;
var upper = nextNode + t;
result += visitedNodes.GetCountLessThanOrEqualTo(upper) - visitedNodes.GetCountLessThanOrEqualTo(lower - 1);
++node.CurrentChildIndex;
visitedNodes.Add(nextNode);
stack.Push(new StackElement { Lable = nextNode, CurrentChildIndex = 0 });
}
}
Console.WriteLine(result);
}
