#include <bits/stdc++.h>
using namespace std;
const int N = 200 * 1000 + 10;
const int K = 6;
int n, k;
vector<int> g[N];
long long res = 0;
struct Data {
  long long sum_at[K];
  long long cnt_at[K];
  Data() {
    fill(sum_at, sum_at + K, 0);
    fill(cnt_at, cnt_at + K, 0);
  }
  Data shift() const {
    Data new_data;
    for (int i = 0; i < k; i++) {
      new_data.sum_at[i] = sum_at[(i - 1 + k) % k];
      new_data.cnt_at[i] = cnt_at[(i - 1 + k) % k];
    }
    if (k > 1)
      new_data.sum_at[1] += new_data.cnt_at[1];
    else
      new_data.sum_at[0] += new_data.cnt_at[0];
    return new_data;
  }
  void unite(Data rhs) {
    rhs = rhs.shift();
    for (int m1 = 0; m1 < k; m1++)
      for (int m2 = 0; m2 < k; m2++) {
        res += sum_at[m1] * rhs.cnt_at[m2] + cnt_at[m1] * rhs.sum_at[m2];
        if (k > 1 && m1 && m2 && m1 + m2 <= k)
          res -= cnt_at[m1] * rhs.cnt_at[m2];
      }
    for (int i = 0; i < k; i++) {
      sum_at[i] += rhs.sum_at[i];
      cnt_at[i] += rhs.cnt_at[i];
    }
  }
  void print() {
    for (int i = 0; i < k; i++) cerr << cnt_at[i] << " " << sum_at[i] << endl;
    cerr << endl;
  }
};
Data dfs(int v, int par) {
  Data res;
  res.cnt_at[0]++;
  for (int to : g[v])
    if (to != par) {
      res.unite(dfs(to, v));
    }
  return res;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(nullptr);
  cin >> n >> k;
  for (int i = 0; i < n - 1; i++) {
    int a, b;
    cin >> a >> b;
    --a;
    --b;
    g[a].push_back(b);
    g[b].push_back(a);
  }
  dfs(0, 0);
  cout << res << endl;
}
