#include <bits/stdc++.h>
using namespace std;
vector<int> v[200010];
int subtree[200010][10], tree[200010][10], p[10], D[200010], odl[200010], n, k,
    a, b;
bool bylem[200010];
long long sumka, suma, add, x;
void DFSdp(int w) {
  bylem[w] = true;
  sumka += odl[w];
  subtree[w][0] = D[w] = 1;
  for (int i = 0; i < v[w].size(); i++) {
    if (!bylem[v[w][i]]) {
      odl[v[w][i]] = odl[w] + 1;
      DFSdp(v[w][i]);
      D[w] += D[v[w][i]];
      for (int j = 0; j < k; j++) {
        subtree[w][j] += subtree[v[w][i]][(j + k - 1) % k];
      }
    }
  }
}
void DFSsum(int w, long long sum) {
  suma += sum;
  for (int i = 1; i < k; i++) {
    add += tree[w][i] * (k - i);
  }
  bylem[w] = true;
  for (int i = 0; i < v[w].size(); i++) {
    if (!bylem[v[w][i]]) {
      for (int j = 0; j < k; j++) {
        p[j] = tree[w][j] - subtree[v[w][i]][(j + k - 1) % k];
      }
      for (int j = 0; j < k; j++) {
        tree[v[w][i]][(j + 1) % k] = p[j] + subtree[v[w][i]][(j + 1) % k];
      }
      DFSsum(v[w][i], sum - D[v[w][i]] + n - D[v[w][i]]);
    }
  }
}
int main() {
  scanf("%d%d", &n, &k);
  for (int i = 1; i < n; i++) {
    scanf("%d%d", &a, &b);
    v[a].push_back(b), v[b].push_back(a);
  }
  DFSdp(1);
  for (int i = 1; i <= n; i++) {
    bylem[i] = false;
  }
  for (int i = 0; i < k; i++) {
    tree[1][i] = subtree[1][i];
  }
  DFSsum(1, sumka);
  printf("%lld", ((suma >> 1) + (add >> 1)) / k);
  return 0;
}
