#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
const int maxn = 2e5 + 1;
int n, k;
vector<vector<int>> tree(maxn);
vector<vector<long long>> dp(maxn, vector<long long>(5)),
    dp2(maxn, vector<long long>(5)), dp3(maxn, vector<long long>(5)),
    dp4(maxn, vector<long long>(5));
void dfs(int x, int p = -1) {
  dp2[x][0]++;
  for (int y : tree[x]) {
    if (y == p) continue;
    dfs(y, x);
  }
  if (p != -1) {
    if (k == 1) {
      dp2[p][0] += dp2[x][0];
      dp[p][0] += dp[x][0] + dp2[x][0];
    } else {
      for (int i = 1; i <= k - 1; i++) {
        dp[p][(i + 1) % k] += dp[x][i];
        dp2[p][(i + 1) % k] += dp2[x][i];
      }
      dp[p][1] += dp[x][0] + dp2[x][0];
      dp2[p][1] += dp2[x][0];
    }
  }
}
void dfs2(int x, int p = -1) {
  for (int y : tree[x]) {
    if (y == p) continue;
    if (k == 1) {
      dp3[y][0] = dp3[x][0] + n - 2 * dp2[y][0];
    } else {
      for (int i = 1; i <= k - 1; i++) {
        int j = (i + 1) % k;
        dp3[y][j] =
            dp3[x][i] - dp[y][i - 1] + dp[y][j] - (i == 1 ? dp2[y][i - 1] : 0);
        dp4[y][j] = dp4[x][i] - dp2[y][i - 1] + dp2[y][j];
      }
      dp3[y][1] =
          dp3[x][0] + dp4[x][0] - dp2[y][k - 1] - dp[y][k - 1] + dp[y][1];
      dp4[y][1] = dp4[x][0] - dp2[y][k - 1] + dp2[y][1];
    }
    dfs2(y, x);
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k;
  for (int i = 0; i < n - 1; i++) {
    int x, y;
    cin >> x >> y;
    tree[x].push_back(y);
    tree[y].push_back(x);
  }
  dfs(1);
  for (int i = 0; i < k; i++) {
    dp3[1][i] = dp[1][i];
    dp4[1][i] = dp2[1][i];
  }
  dfs2(1);
  long long ans = 0;
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j < k; j++) {
      ans += dp3[i][j];
    }
  }
  cout << ans / 2 << '\n';
  return 0;
}
