#include <bits/stdc++.h>
using namespace std;
const long long N = 2e5 + 100;
long long n, k;
struct Node {
  long long y, Next;
} e[2 * N];
long long len, linkk[N];
long long f[N][10];
void Insert(long long x, long long y) {
  e[++len] = (Node){y, linkk[x]};
  linkk[x] = len;
}
long long siz[N];
void dfs(long long x, long long faa) {
  siz[x] = 1;
  for (long long i = linkk[x]; i; i = e[i].Next) {
    long long y = e[i].y;
    if (y == faa) continue;
    dfs(y, x);
    siz[x] += siz[y];
    f[x][0] += f[y][k - 1] + siz[y];
    for (long long j = 1; j < k; j++) f[x][j] = f[x][j] + f[y][j - 1];
  }
}
void Dfs(long long x, long long faa) {
  long long g[5] = {};
  if (faa) {
    g[0] = f[faa][0] - f[x][k - 1] - siz[x];
    for (long long i = 1; i <= k; i++) g[i] = f[faa][i] - f[x][i - 1];
    f[x][0] += g[k - 1] + n - siz[x];
    for (long long i = 1; i <= k; i++) f[x][i] += g[i - 1];
  }
  for (long long i = linkk[x]; i; i = e[i].Next)
    if (e[i].y != faa) Dfs(e[i].y, x);
}
signed main() {
  scanf("%lld %lld", &n, &k);
  for (long long i = 1, x, y; i < n; i++)
    scanf("%lld %lld", &x, &y), Insert(x, y), Insert(y, x);
  dfs(1, 0);
  Dfs(1, 0);
  long long ans = 0;
  for (long long i = 1; i <= n; i++) ans += f[i][0];
  cout << ans / 2;
  return 0;
}
