#include <bits/stdc++.h>
using namespace std;
int n, k;
vector<int> v[200010];
long long cnt = 0, ch[200010][10], sm[200010][10], tmp[10];
void dfs(int x, int p) {
  for (auto e : v[x]) {
    if (e != p) {
      dfs(e, x);
      for (int i = 0; i < k; ++i) {
        ch[x][(i + 1) % k] += ch[e][i];
        sm[x][(i + 1) % k] += sm[e][i];
      }
      ++ch[x][1 % k];
      sm[x][1 % k] += ch[e][0] + 1;
    }
  }
  for (auto e : v[x]) {
    if (e != p) {
      for (int i = 0; i < k; ++i) {
        for (int j = 0; j < k; ++j) {
          long long tmp1 = sm[e][(i + k - 1) % k],
                    tmp2 = sm[x][j] - sm[e][(j + k - 1) % k];
          long long ch1 = ch[e][(i + k - 1) % k],
                    ch2 = ch[x][j] - ch[e][(j + k - 1) % k];
          if (i == 1 % k) {
            tmp1 += ch[e][0] + 1;
            ++ch1;
          }
          if (j == 1 % k) {
            tmp2 -= ch[e][0] + 1;
            --ch2;
          }
          cnt += tmp1 * ch2 + tmp2 * ch1;
          if (i && j && i + j <= k) {
            cnt -= ch1 * ch2;
          }
        }
      }
    }
  }
}
int main() {
  cin >> n >> k;
  memset(ch, 0, sizeof ch);
  memset(sm, 0, sizeof sm);
  for (int i = 1; i < n; ++i) {
    int x, y;
    cin >> x >> y;
    v[x].push_back(y);
    v[y].push_back(x);
  }
  dfs(1, 0);
  cnt >>= 1;
  for (int i = 1; i <= n; ++i) {
    for (int j = 0; j < k; ++j) {
      cnt += sm[i][j];
    }
  }
  cout << cnt << endl;
  return 0;
}
