#include <bits/stdc++.h>
using namespace std;
inline void pi(int x) {
  if (x == 0) {
    putchar('0');
    return;
  }
  char c[10];
  int k = 0;
  if (x < 0) {
    putchar('-');
    x = -x;
  }
  while (x) {
    int nx = x / 10;
    c[k++] = x - nx * 10;
    x = nx;
  }
  while (k--) {
    putchar(c[k] + '0');
  }
}
inline void pin(const int& x) {
  pi(x);
  putchar('\n');
};
inline void pl(long long x) {
  if (x == 0) {
    putchar('0');
    return;
  }
  char c[19];
  int k = 0;
  if (x < 0) {
    putchar('-');
    x = -x;
  }
  while (x) {
    long long nx = x / 10;
    c[k++] = x - nx * 10;
    x = nx;
  }
  while (k--) {
    putchar(c[k] + '0');
  }
}
inline void pln(const long long& x) {
  pl(x);
  putchar('\n');
};
inline void gi(int& val) {
  val = 1;
  char c;
  do {
    c = getchar();
  } while (c != '-' && (c < '0' || c > '9'));
  int zn = 1;
  if (c == '-') {
    zn = -1;
    c = getchar();
  }
  val = c - '0';
  c = getchar();
  while (c >= '0' && c <= '9') {
    val *= 10;
    val += c - '0';
    c = getchar();
  }
  val *= zn;
}
inline void gl(long long& val) {
  val = 1;
  char c;
  do {
    c = getchar();
  } while (c != '-' && (c < '0' || c > '9'));
  int zn = 1;
  if (c == '-') {
    zn = -1;
    c = getchar();
  }
  val = c - '0';
  c = getchar();
  while (c >= '0' && c <= '9') {
    val *= 10;
    val += c - '0';
    c = getchar();
  }
  val *= zn;
}
inline void gl(long long& val1, long long& val2) {
  gl(val1);
  gl(val2);
}
inline void gi(int& val1, int& val2) {
  gi(val1);
  gi(val2);
}
inline void gl(long long& val1, long long& val2, long long& val3) {
  gl(val1);
  gl(val2);
  gl(val3);
}
inline void gi(int& val1, int& val2, int& val3) {
  gi(val1);
  gi(val2);
  gi(val3);
}
inline void mygets(char* b) {
  int i = 0;
  for (;; ++i) {
    const char c = getchar();
    if (c == '\n' || c == EOF) {
      break;
    }
    b[i] = c;
  }
  b[i] = '\0';
}
inline void mygets(string& b) {
  int i = 0;
  for (;; ++i) {
    const char c = getchar();
    if (c == '\n' || c == EOF) {
      break;
    }
    b.push_back(c);
  }
}
inline void mygets(char& b) {
  b = getchar();
  getchar();
}
inline void myputs(const string& b) {
  for (int i = 0; i < b.size(); ++i) {
    putchar(b[i]);
  }
}
inline void putsn(const string& b) {
  myputs(b);
  putchar('\n');
}
inline void myputs(const char& b) { putchar(b); }
inline void putsn(const char& b) {
  putchar(b);
  putchar('\n');
}
const int N = 2e5 + 7, M = 150000, mod = 1000000007, inf = 1000000007;
const long long lmod = 1000000007, linf = 1e18 + 77;
const long double eps = 1e-14;
vector<int> g[N];
bool used[N];
int n, k;
long long r[N][5];
int c[N][5];
long long ans = 0;
void go(int v) {
  used[v] = 1;
  c[v][0] = 1;
  for (auto to : g[v]) {
    if (!used[to]) {
      go(to);
      for (int i = k - 1; i > 0; i--) {
        swap(r[to][i], r[to][i - 1]);
        swap(c[to][i], c[to][i - 1]);
      }
      for (int i = 0; i < k; i++) {
        r[to][i] += c[to][i];
      }
      for (int i = 0; i < k; i++) {
        for (int j = 0; j < k; j++) {
          int ost = (i + j) % k;
          if (ost == 0) {
            ans += (r[v][i] * c[to][j] + r[to][j] * c[v][i]) / k;
          } else {
            ans += (r[v][i] * c[to][j] + r[to][j] * c[v][i] -
                    (long long)ost * c[to][j] * c[v][i]) /
                       k +
                   (long long)c[to][j] * c[v][i];
          }
        }
      }
      for (int i = 0; i < k; i++) {
        r[v][i] += r[to][i];
        c[v][i] += c[to][i];
      }
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  gi(n, k);
  for (int i = 0; i < n - 1; i++) {
    int u, v;
    gi(u, v);
    g[u].push_back(v);
    g[v].push_back(u);
  }
  go(1);
  pln(ans);
}
