#include <bits/stdc++.h>
using namespace std;
void init() {}
const int N = (int)2e5 + 34;
vector<int> es[N];
int n, k;
long long num[N][6];
long long ful[N][6];
long long ans = 0;
void go(int v, int pr) {
  if (es[v].size() == 0) {
    return;
  }
  for (int i = 0; i < (int)es[v].size(); i++)
    if (es[v][i] == pr) swap(es[v][i], es[v].back());
  if (es[v].back() == pr) es[v].pop_back();
  for (auto w : es[v]) {
    go(w, v);
    for (int i = k - 1; i >= 0; i--) {
      num[w][i + 1] = num[w][i];
      ful[w][i + 1] = ful[w][i];
    }
    num[w][1]++;
    num[w][0] = num[w][k];
    ful[w][0] = ful[w][k] + num[w][k];
    for (int i = 0; i < k; i++) {
      num[v][i] += num[w][i];
      ful[v][i] += ful[w][i];
    }
  }
  for (int o = 0; o < k; o++) {
    ans += 2 * (ful[v][o] + ((o + k - 1) / k) * num[v][o]);
  }
  long long num1, ful1;
  for (auto w : es[v]) {
    for (int o0 = 0; o0 < k; o0++) {
      for (int o1 = 0; o1 < k; o1++) {
        num1 = num[v][o1] - num[w][o1];
        ful1 = ful[v][o1] - ful[w][o1];
        ans += ful[w][o0] * num1 + ful1 * num[w][o0];
        ans += ((o0 + o1 + k - 1) / k) * num1 * num[w][o0];
      }
    }
  }
}
int main() {
  init();
  int v1, v2;
  scanf("%d%d", &n, &k);
  for (int i = 1; i < n; i++) {
    scanf("%d%d", &v1, &v2);
    v1--;
    v2--;
    es[v1].push_back(v2);
    es[v2].push_back(v1);
  }
  go(0, -1);
  printf("%I64d\n", ans / 2);
  return 0;
}
