#include <bits/stdc++.h>
using namespace std;
template <typename T1, typename T2>
istream& operator>>(istream& in, pair<T1, T2>& a) {
  in >> a.first >> a.second;
  return in;
}
template <typename T1, typename T2>
ostream& operator<<(ostream& out, pair<T1, T2> a) {
  out << a.first << " " << a.second;
  return out;
}
template <typename T, typename T1>
T amax(T& a, T1 b) {
  if (b > a) a = b;
  return a;
}
template <typename T, typename T1>
T amin(T& a, T1 b) {
  if (b < a) a = b;
  return a;
}
const long long INF = 1e18;
const int32_t M = 1e9 + 7;
const int32_t MM = 998244353;
const long long N = 2e5 + 5;
long long n, k;
long long ans = 0;
long long dp[N][5], tot[N], sz[N];
vector<long long> v[N];
void dfs(long long z, long long p) {
  sz[z] = 1;
  dp[z][0] = 1;
  reverse((v[z]).begin(), (v[z]).end());
  for (long long x : v[z]) {
    if (x == p) continue;
    dfs(x, z);
    for (long long i = 0; i < k; i++) {
      for (long long j = 0; j < k; j++) {
        long long val = (i + j + k - 1) / k;
        ans += val * dp[x][(i + k - 1) % k] * (dp[z][j]);
      }
    }
    sz[z] += sz[x];
    for (long long i = 0; i < k; i++) {
      dp[z][(i + 1) % k] += dp[x][i];
    }
    tot[z] += tot[x] + dp[x][k - 1];
  }
  for (long long x : v[z]) {
    if (x == p) continue;
    ans += (sz[z] - sz[x]) * (tot[x] + dp[x][k - 1]);
  }
}
void solve() {
  cin >> n >> k;
  for (long long i = 1; i < n; i++) {
    long long x, y;
    cin >> x >> y;
    v[x].push_back(y);
    v[y].push_back(x);
  }
  dfs(1, 0);
  cout << ans;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  while (t--) solve();
  return 0;
}
