#include <bits/stdc++.h>
using namespace std;
const int INF = 2 * int(1e9);
const long long INFll = 1ll * int(1e9) * int(1e9);
const int MOD = 1000000007;
template <typename T, typename Q>
ostream& operator<<(ostream& out, pair<T, Q>& a) {
  out << a.first << " " << a.second;
  return out;
}
template <typename T, typename Q>
istream& operator>>(istream& in, pair<T, Q>& a) {
  in >> a.first >> a.second;
  return in;
}
template <typename T>
istream& operator>>(istream& in, vector<T>& a) {
  for (int i = 0; i < a.size(); ++i) in >> a[i];
  return in;
}
template <typename T>
ostream& operator<<(ostream& out, vector<T> a) {
  for (int i = 0; i < a.size(); ++i)
    if (i == a.size() - 1)
      out << a[i];
    else
      out << a[i] << " ";
  return out;
}
const int N = 200005;
int n, k;
long long dp[N][6];
long long up[N][6];
int cnt[N][6];
int upcnt[N][6];
vector<int> g[N];
long long ans = 0;
void dfs(int v, int anc = -1) {
  cnt[v][0] = 1;
  for (int i = 0; i < k; ++i) dp[v][i] = 0;
  for (int to : g[v])
    if (to != anc) {
      dfs(to, v);
      for (int i = 0; i < k; ++i) cnt[v][(i + 1) % k] += cnt[to][i];
      for (int i = 0; i < k; ++i)
        dp[v][(i + 1) % k] += dp[to][i] + cnt[to][i] * (i == 0);
    }
}
void dfs2(int v, int anc = -1) {
  for (int i = 0; i < k; ++i) ans += dp[v][i] + up[v][i];
  upcnt[v][0] += 1;
  for (int to : g[v])
    if (to != anc)
      for (int i = 0; i < k; ++i) {
        up[v][(i + 1) % k] += dp[to][i] + cnt[to][i] * (i == 0);
        upcnt[v][(i + 1) % k] += cnt[to][i];
      }
  for (int to : g[v]) {
    if (to != anc) {
      for (int i = 0; i < k; ++i) {
        up[v][(i + 1) % k] -= dp[to][i] + cnt[to][i] * (i == 0);
        upcnt[v][(i + 1) % k] -= cnt[to][i];
      }
      for (int i = 0; i < k; ++i) {
        up[to][(i + 1) % k] += up[v][i] + upcnt[v][i] * (i == 0);
        upcnt[to][(i + 1) % k] += upcnt[v][i];
      }
      dfs2(to, v);
      for (int i = 0; i < k; ++i) {
        up[v][(i + 1) % k] += dp[to][i] + cnt[to][i] * (i == 0);
        upcnt[v][(i + 1) % k] += cnt[to][i];
      }
    }
  }
}
int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cin >> n >> k;
  for (int i = 1; i < n; ++i) {
    int x, y;
    cin >> x >> y;
    x--, y--;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  dfs(0);
  dfs2(0);
  if (0) cerr << ans << endl;
  cout << ans / 2;
  if (0)
    cerr << fixed << setprecision(0)
         << "TIME = " << clock() / (long double)CLOCKS_PER_SEC * 1000 << "\n";
  return 0;
}
