#include <bits/stdc++.h>
using namespace std;
const int N = 3e5 + 10;
inline int read() {
  char ch = getchar();
  int x = 0, f = 1;
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = (x << 1) + (x << 3) - '0' + ch;
    ch = getchar();
  }
  return x * f;
}
int n, k, size[N];
long long ans, f[N][5];
vector<int> g[N];
void dfs(int u, int fa, int d) {
  size[u] = 1;
  f[u][d % k] = 1;
  for (auto &v : g[u]) {
    if (v == fa) continue;
    dfs(v, u, d + 1);
    size[u] += size[v];
    ans += 1ll * (n - size[v]) * size[v];
    for (int i = 0; i < k; i++) {
      for (int j = 0; j < k; j++) {
        int z = ((i + j - 2 * d) % k + k) % k;
        z = (k - z) % k;
        ans += 1ll * z * f[u][i] * f[v][j];
      }
    }
    for (int i = 0; i < k; i++) f[u][i] += f[v][i];
  }
}
int main() {
  n = read(), k = read();
  for (int i = 1; i <= n - 1; i++) {
    int a = read(), b = read();
    g[a].push_back(b);
    g[b].push_back(a);
  }
  dfs(1, 0, 0);
  printf("%lld\n", ans / k);
}
