#include <cstdio>
#include <cctype>

template <typename T> T read() {
  T res = 0, f = 1;
  char ch = getchar();
  for (; !isdigit(ch); ch = getchar()) if (ch == '-') f = -1;
  for (; isdigit(ch); ch = getchar()) res = (res << 3) + (res << 1) + (ch ^ 48);
  return res * f;
}

void write(__int128 x, char ed = '\n') {
  if (x < 0) x = -x, putchar('-');
  static int sta[64], top = 0;
  do {
    sta[++top] = x % 10;
    x /= 10;
  } while (x);
  while (top) {
    putchar(sta[top--] ^ 48);
  }
  putchar(ed);
}

template <typename T> void write(T x, char ed = '\n') {
  write((__int128)x, ed);
}

#include <algorithm>

const int MAXN = 2e6 + 10;

struct EDGE {
  int v, w, next;
} edge[MAXN << 1];

int head[MAXN], edgeNum = 1;
void AddEdge(int u, int v, int w) {
  edge[++edgeNum] = {v, w, head[u]};
  head[u] = edgeNum;
}

int depth[MAXN], far, fa[MAXN];
void dfs1(int u, int fa) {
  ::fa[u] = fa;
  for (int i = head[u]; i; i = edge[i].next) {
    int v = edge[i].v;
    if (v == fa) continue;
    depth[v] = depth[u] + 1;
    if (depth[v] > depth[far]) far = v;
    dfs1(v, u);
  }
}

int dp[MAXN], d;
void dfs2(int u, int fa) {
  for (int i = head[u]; i; i = edge[i].next) {
    int v = edge[i].v, w = edge[i].w;
    if (v == fa) continue;
    dfs2(v, u);
    d = std::max(d, dp[u] + dp[v] + w);
    dp[u] = std::max(dp[u], dp[v] + w);
  }
}

int n, k;
int L1, L2;

int main(int argc, char **argv) {
  #ifdef LOCAL
    freopen("!input.in", "r", stdin);
    freopen("!output.out", "w", stdout);
  #elif defined(FS)
    freopen(argv[1], "r", stdin);
    freopen(argv[2], "w", stdout);
  #else
    freopen("xunluo.in", "r", stdin);
    freopen("xunluo.out", "w", stdout);
  #endif
  n = read<int>(), k = read<int>();
  for (int i = 1; i <= n - 1; ++i) {
    int u = read<int>(), v = read<int>();
    AddEdge(u, v, 1);
    AddEdge(v, u, 1);
  }

  dfs1(1, 0);
  depth[far] = 0;
  dfs1(far, 0);

  L1 = depth[far];
  while (far) {
    for (int i = head[far]; i; i = edge[i].next) {
      if (edge[i].v == fa[far]) {
        edge[i].w = -1;
        edge[i ^ 1].w = -1;
        break;
      }
    }
    far = fa[far];
  }

  dfs2(1, 0);
  L2 = d;

  write(2 * n - L1 - (k == 2 ? L2 : 1));
  return 0;
}