#include <bits/stdc++.h>
using namespace std;
long long Ans, sum, f[200005][6], g[200005][6];
int n, m, cnt;
int size[200005];
int head[200005], to[400005], Next[400005];
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = (x << 1) + (x << 3) + ch - '0';
    ch = getchar();
  }
  return x * f;
}
inline void add(int u, int v) {
  to[++cnt] = v;
  Next[cnt] = head[u];
  head[u] = cnt;
}
void Dfs1(int u, int fa) {
  size[u] = 1;
  for (register int i = head[u]; i; i = Next[i]) {
    int v = to[i];
    if (v == fa) continue;
    Dfs1(v, u);
    size[u] += size[v];
  }
  if (u != 1) sum += size[u];
  return;
}
void Dfs2(int u, int fa) {
  Ans += sum;
  for (register int i = head[u]; i; i = Next[i]) {
    int v = to[i];
    if (v == fa) continue;
    size[u] -= size[v];
    sum -= size[v];
    size[v] += size[u];
    sum += size[u];
    Dfs2(v, u);
    size[v] -= size[u];
    sum -= size[u];
    size[u] += size[v];
    sum += size[v];
  }
  return;
}
void DP1(int u, int fa) {
  for (register int i = head[u]; i; i = Next[i]) {
    int v = to[i];
    if (v == fa) continue;
    DP1(v, u);
    for (register int k = 1; k < m; ++k) {
      f[u][(k + 1) % m] += f[v][k];
      g[u][(k + 1) % m] += g[v][k];
    }
    g[u][1] += 1 + g[v][0];
    f[u][1] += 1 + g[v][0] + f[v][0];
  }
  return;
}
void DP2(int u, int fa) {
  for (register int i = 0; i < m; ++i) Ans += f[u][i];
  for (register int i = head[u]; i; i = Next[i]) {
    int v = to[i];
    if (v == fa) continue;
    for (register int k = 1; k < m; ++k) {
      f[u][(k + 1) % m] -= f[v][k];
      g[u][(k + 1) % m] -= g[v][k];
    }
    g[u][1] -= 1 + g[v][0];
    f[u][1] -= 1 + g[v][0] + f[v][0];
    for (register int k = 1; k < m; ++k) {
      f[v][(k + 1) % m] += f[u][k];
      g[v][(k + 1) % m] += g[u][k];
    }
    g[v][1] += 1 + g[u][0];
    f[v][1] += 1 + g[u][0] + f[u][0];
    DP2(v, u);
    g[v][1] -= 1 + g[u][0];
    f[v][1] -= 1 + g[u][0] + f[u][0];
    for (register int k = 1; k < m; ++k) {
      f[v][(k + 1) % m] -= f[u][k];
      g[v][(k + 1) % m] -= g[u][k];
    }
    g[u][1] += 1 + g[v][0];
    f[u][1] += 1 + g[v][0] + f[v][0];
    for (register int k = 1; k < m; ++k) {
      f[u][(k + 1) % m] += f[v][k];
      g[u][(k + 1) % m] += g[v][k];
    }
  }
  return;
}
int main() {
  n = read();
  m = read();
  for (register int i = 2; i <= n; ++i) {
    int u, v;
    u = read();
    v = read();
    add(u, v);
    add(v, u);
  }
  if (m == 1) {
    Dfs1(1, 0);
    Dfs2(1, 0);
  } else {
    DP1(1, 0);
    DP2(1, 0);
  }
  printf("%lld\n", Ans >> 1LL);
  return 0;
}
