#include <bits/stdc++.h>
using namespace std;
long long n, k, u, v, dp[200010][5], len[200010][5], child[200010][5],
    num[200010][5], rem[5], ram[5], ans = 0;
vector<long long> graph[200010];
void dfs(long long u) {
  memset(rem, 0, sizeof(rem));
  memset(ram, 0, sizeof(ram));
  long long p = -1, s;
  for (long long i = 0; i < k; i++) child[u][i] = dp[u][i] = len[u][i] = 0;
  for (long long i = 0; i < graph[u].size(); i++) {
    long long v = graph[u][i];
    if (dp[v][0] == -1) {
      dfs(v);
      child[u][0] += child[v][k - 1],
          dp[u][0] += dp[v][k - 1] + child[v][k - 1],
          len[u][0] += len[v][0] + dp[v][0],
          num[u][0] += num[v][0] + child[v][0];
      for (long long j = 1; j < k; j++) {
        child[u][j] += child[v][j - 1],
            dp[u][j] += dp[v][j - 1] + child[v][j - 1],
            len[u][j] += len[v][j] + dp[v][j],
            num[u][j] += num[v][j] + child[v][j];
      }
    } else
      p = v;
  }
  if (p == -1 || graph[u].size() > 2) {
    for (long long j = 0; j < graph[u].size(); j++) {
      long long v = graph[u][j];
      if (v != p) {
        for (long long i = 0; i < k; i++)
          rem[i] = dp[v][i] + child[v][i], ram[i] = child[v][i];
        s = j + 1;
        break;
      }
    }
    for (long long i = s; i < graph[u].size(); i++) {
      long long v = graph[u][i];
      if (v != p) {
        for (long long j = 0; j < k; j++) {
          for (long long l = 0; l < k; l++)
            len[u][(j + l + 2) % k] +=
                rem[j] * child[v][l] + (dp[v][l] + child[v][l]) * ram[j],
                num[u][(j + l + 2) % k] += ram[j] * child[v][l];
        }
        for (long long j = 0; j < k; j++)
          rem[j] += dp[v][j] + child[v][j], ram[j] += child[v][j];
      }
    }
  }
  child[u][0]++;
}
int main() {
  memset(dp, -1, sizeof(dp));
  scanf("%lld%lld", &n, &k);
  for (long long i = 1; i < n; i++) {
    scanf("%lld%lld", &u, &v);
    graph[u].push_back(v);
    graph[v].push_back(u);
  }
  dfs(1);
  ans = len[1][0] + dp[1][0];
  for (long long i = 1; i < k; i++)
    ans += len[1][i] + dp[1][i] + (num[1][i] + child[1][i]) * (k - i);
  printf("%lld", ans / k);
}
