#include <bits/stdc++.h>
using namespace std;
using namespace std;
const int K = 7;
const int N = 200500;
int n, k;
int sz[K][N], ups[K][N];
long long len[K][N], ways[K][N];
long long f[K][N], fuh[K][N], f1[K][N], fup[K][N];
vector<int> g[N];
void dfs(int ver, int prev) {
  f[0][ver] = 1;
  sz[0][ver] = 1;
  for (int i = 0; i < (int)g[ver].size(); i++) {
    int to = g[ver][i];
    if (to != prev) {
      dfs(to, ver);
      for (int j = 0; j < k; j++) {
        sz[(j + 1) % k][ver] += sz[j][to];
        f[(j + 1) % k][ver] += f[j][to];
        f1[(j + 1) % k][ver] += (f1[j][to] + 1LL * sz[j][to]);
      }
    }
  }
}
void dfs_up(int ver, int prev) {
  ++fup[0][ver];
  ++ups[0][ver];
  long long all[k];
  long long kek[k];
  int ps[k];
  for (int j = 0; j < k; ++j) ps[j] = 0;
  for (int j = 0; j < k; ++j) all[j] = kek[j] = 0LL;
  for (int i = 0; i < (int)g[ver].size(); i++) {
    int to = g[ver][i];
    if (to != prev) {
      for (int j = 0; j < k; j++) {
        all[j] += f[j][to];
        ps[j] += sz[j][to];
        kek[j] += f1[j][to];
      }
    }
  }
  for (int i = 0; i < (int)g[ver].size(); i++) {
    int to = g[ver][i];
    if (to == prev) {
      continue;
    }
    for (int j = 0; j < k; j++) {
      all[j] -= f[j][to];
      ps[j] -= sz[j][to];
      kek[j] -= f1[j][to];
    }
    for (int j = 0; j < k; j++) {
      fup[(j + 2) % k][to] += all[j];
      fup[(j + 1) % k][to] += fup[j][ver];
      fuh[(j + 2) % k][to] += (kek[j] + 2LL * ps[j]);
      fuh[(j + 1) % k][to] += (fuh[j][ver] + 1LL * ups[j][ver]);
      ups[(j + 1) % k][to] += ups[j][ver];
      ups[(j + 2) % k][to] += ps[j];
    }
    for (int j = 0; j < k; j++) {
      all[j] += f[j][to];
      ps[j] += sz[j][to];
      kek[j] += f1[j][to];
    }
  }
  for (int i = 0; i < (int)g[ver].size(); i++) {
    int to = g[ver][i];
    if (to != prev) {
      dfs_up(to, ver);
    }
  }
}
int main() {
  scanf("%d%d", &n, &k);
  for (int i = 1; i < n; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    g[u].push_back(v);
    g[v].push_back(u);
  }
  dfs(1, 1);
  dfs_up(1, 1);
  long long ans = 0LL;
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j < k; j++) {
      ways[j][i] = f[j][i] + fup[j][i];
      len[j][i] = f1[j][i] + fuh[j][i];
      ans =
          ans + (len[j][i] - ways[j][i] * j) / k + 1LL * ways[j][i] * (j != 0);
    }
  }
  ans /= 2LL;
  cout << ans;
  puts("");
  return 0;
}
