#include <bits/stdc++.h>
using namespace std;
const long long N = 2e5 + 5;
const long long M = 1e6 + 5;
const long long mod = 1e8 + 7;
const long long inf = 1e9;
inline long long read() {
  long long s = 0;
  register bool neg = 0;
  register char c = getchar();
  for (; c < '0' || c > '9'; c = getchar()) neg |= (c == '-');
  for (; c >= '0' && c <= '9'; s = s * 10 + (c ^ 48), c = getchar())
    ;
  s = (neg ? -s : s);
  return s;
}
long long a, b, dp[N][5], f[N];
vector<long long> st[N];
inline void dfs(long long n, long long fa) {
  for (long long i = (0); i <= (((long long)((st[n]).size())) - 1); ++i) {
    long long v = st[n][i];
    if (v == fa) continue;
    dfs(v, n);
    for (long long j = (0); j <= (b - 1); ++j)
      dp[n][j] += dp[v][(j - 1 + b) % b];
    f[1] += dp[v][b - 1];
  }
  dp[n][0]++;
}
inline void Dfs(long long n, long long fa) {
  static long long tmp[5];
  for (long long i = (0); i <= (((long long)((st[n]).size())) - 1); ++i) {
    long long v = st[n][i];
    if (v == fa) continue;
    memset(tmp, 0, sizeof(tmp));
    f[v] -= dp[v][0];
    for (long long j = (0); j <= (b - 1); ++j)
      tmp[j] = dp[n][j] - dp[v][(j - 1 + b) % b];
    f[v] += tmp[0] + f[n];
    for (long long j = (0); j <= (b - 1); ++j) dp[v][j] += tmp[(j - 1 + b) % b];
    Dfs(v, n);
  }
}
signed main() {
  a = read();
  b = read();
  long long x, y;
  for (long long i = (1); i <= (a - 1); ++i) {
    x = read();
    y = read();
    st[x].push_back(y);
    st[y].push_back(x);
  }
  dfs(1, 0);
  for (long long i = (1); i <= (b - 1); ++i) f[1] += dp[1][i];
  Dfs(1, 0);
  long long ans = 0;
  for (long long i = (1); i <= (a); ++i) ans += f[i];
  printf("%lld", ans / 2);
  return 0;
}
