#include <bits/stdc++.h>
using namespace std;
#pragma comment(linker, "/STACK:102400000,102400000")
const long long INF = 1e18 + 1LL;
const double Pi = acos(-1.0);
const int N = 5e5 + 10, M = 1e3 + 20, mod = 1e9 + 7, inf = 2e9;
vector<int> G[N];
long long dp[N][10], fs[N][10];
long long ans = 0;
int n, k, a, b;
void dfs(int u, int f) {
  dp[u][0] = 1;
  for (int i = 0; i < G[u].size(); ++i) {
    int to = G[u][i];
    if (to == f) continue;
    dfs(to, u);
    for (int j = 0; j <= k; ++j) {
      for (int h = 0; h <= k; ++h) {
        if (!dp[u][j] || !dp[to][h]) continue;
        long long tmp = j + h + 1;
        if (tmp % k)
          tmp = tmp / k + 1;
        else
          tmp = tmp / k;
        ans += tmp * dp[to][h] * dp[u][j] + fs[u][j] * dp[to][h] +
               fs[to][h] * dp[u][j];
      }
    }
    for (int j = 1; j <= k; ++j)
      dp[u][j] += dp[to][j - 1], fs[u][j] += fs[to][j - 1];
    dp[u][1] += dp[to][k];
    fs[u][1] += fs[to][k] + dp[to][k];
  }
}
int main() {
  scanf("%d%d", &n, &k);
  for (int i = 1; i < n; ++i) {
    scanf("%d%d", &a, &b);
    G[a].push_back(b);
    G[b].push_back(a);
  }
  dfs(1, 0);
  cout << ans << endl;
  return 0;
}
