#include <bits/stdc++.h>
using namespace std;
void fun() {}
long long int md = 1e9 + 7;
long long int __gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return __gcd(b, a % b);
}
long long int poww(long long int a, long long int b, long long int md) {
  if (b < 0) return 0;
  if (a == 0) return 0;
  long long int res = 1;
  while (b) {
    if (b & 1) {
      res = (1ll * res * a) % md;
    }
    a = (1ll * a * a) % md;
    b >>= 1;
  }
  return res;
}
long long int poww(long long int a, long long int b) {
  if (b < 0) return 0;
  if (a == 0) return 0;
  long long int res = 1;
  while (b) {
    if (b & 1) {
      res = (1ll * res * a);
    }
    a = (1ll * a * a);
    b >>= 1;
  }
  return res;
}
void ainp(long long int arr[], long long int n) {
  for (long long int i = 1; i <= n; i++) cin >> arr[i];
}
long long int divide(long long int a, long long int b, long long int md) {
  long long int rr = a * (poww(b, md - 2, md));
  rr %= md;
  return rr;
}
const long long int size = 2e5 + 1;
long long int n, k;
vector<long long int> g[size];
long long int mods[size][5], nodecount[size];
long long int answer;
void dfs(long long int par, long long int gpar) {
  nodecount[par] = 1;
  mods[par][0] = 1;
  for (long long int child : g[par]) {
    if (child == gpar) continue;
    dfs(child, par);
    for (long long int i = 0; i < k; i++) {
      for (long long int j = 0; j < k; j++) {
        long long int num = (i + j + 1) % k;
        long long int needed = (k - num) % k;
        answer += mods[par][i] * mods[child][j] * needed;
      }
    }
    nodecount[par] += nodecount[child];
    for (long long int i = 0; i < k; i++)
      mods[par][(i + 1) % k] += mods[child][i % k];
  }
  answer += nodecount[par] * (n - nodecount[par]);
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  fun();
  cin >> n >> k;
  long long int a, b;
  for (long long int i = 1; i < n; i++) {
    cin >> a >> b;
    g[a].push_back(b);
    g[b].push_back(a);
  }
  dfs(1, 1);
  cout << answer / k << "\n";
  return 0;
}
