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#include <bits/stdc++.h>
using namespace std;
template <typename T> inline void read(T &a){
T w=1; a=0;
char ch=getchar();
for(;ch < '0' || ch > '9';ch=getchar()) if(ch == '-') w=-1;
for(;ch>='0'&&ch<='9';ch=getchar()) a=(a<<3)+(a<<1)+(ch^48);
a*=w;
}
template <typename T> inline void ckmax(T &a, T b){a = a > b ? a : b;}
template <typename T> inline void ckmin(T &a, T b){a = a < b ? a : b;}
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define pii pair<int, int>
#define vi vector<int>
#define Debug(x) cout << #x << " = " << x << endl
#define For(i,l,r) for (int i = l; i <= r; ++i)
#define foR(i,l,r) for (int i = l; i >= r; --i)
const int N = 1e6 + 10;
const int V = 1e6 + 10;
vi g[N], G[V], grace[N];
int n, k;
int fa[N], tp[N], son[N], siz[N];
int dfn[N], dfntot, rnk[N], dep[N];
int c[N];
void dfs1 (int u, int father) {
fa[u] = father;
siz[u] = 1; dep[u] = dep[father] + 1;
for (auto v : g[u]) {
if (v == fa[u]) continue;
dfs1(v, u); siz[u] += siz[v];
if (siz[v] > siz[son[u]]) son[u] = v;
}
}
int Node;
void dfs2 (int u, int Top) {
rnk[dfn[u] = ++dfntot] = u; tp[u] = Top;
if (!son[u]) return;
dfs2 (son[u], Top);
for (auto v : g[u]) {
if (v == fa[u] || v == son[u]) continue;
dfs2 (v, v);
}
}
struct SEG {
int ls, rs, k, l, r;
} tr[N << 2];
int build (int l, int r) {
int x = ++Node;
tr[x].l = l; tr[x].r = r;
if (l == r) return G[x].pb(c[rnk[l]]), x;
int mid = l + r >> 1;
tr[x].ls = build (l, mid);
tr[x].rs = build (mid + 1, r);
G[x].pb(tr[x].ls), G[x].pb(tr[x].rs);
return x;
}
void update (int x, int ll, int rr, int mck) {
if (ll <= tr[x].l && tr[x].r <= rr) return G[mck].pb(x), void();
int mid = tr[x].l + tr[x].r >> 1;
if (ll <= mid) update(tr[x].ls, ll, rr, mck);
if (rr > mid) update(tr[x].rs, ll, rr, mck);
}
int rt;
int LCA (int x, int y) {
int fx = tp[x], fy = tp[y];
while (fx != fy) {
if (dep[fx] >= dep[fy]) x = fa[fx];
else y = fa[fy];
fx = tp[x], fy = tp[y];
}
return dep[x] < dep[y] ? x : y;
}
void upd (int x, int y, int Color) {
int fx = tp[x], fy = tp[y];
while (fx != fy) {
if (dep[fx] >= dep[fy]) {
update(rt, dfn[fx], dfn[x], Color), x = fa[fx];
}
else {
update(rt, dfn[fy], dfn[y], Color), y = fa[fy];
}
fx = tp[x], fy = tp[y];
}
if (dfn[x] > dfn[y]) swap(x, y);
update(rt, dfn[x], dfn[y], Color);
}
int lw[V], df[V], deep;
int col[V], sta[V], top, color;
int vis[N];
void tarjan (int u) {
lw[u] = df[u] = ++deep;
vis[sta[++top] = u] = 1;
for (auto v : G[u])
if (!df[v]) tarjan(v), ckmin(lw[u], lw[v]);
else if (vis[v]) ckmin(lw[u], df[v]);
if (lw[u] == df[u]) {
color++;
while (sta[top] != u) {
vis[sta[top]] = false;
col[sta[top--]] = color;
}
vis[sta[top]] = false;
col[sta[top--]] = color;
}
}
int du[N], si[N];
int main() {
read(n); read(k);
For (i, 1, n - 1) {
int x, y; read(x); read(y);
g[x].pb(y), g[y].pb(x);
}
For (i, 1, n) {
read(c[i]);
grace[c[i]].pb(i);
}
dfs1(1, 0), dfs2(1, 1);
Node = k; rt = build(1, n);
For (i, 1, k) {
sort (grace[i].begin(), grace[i].end(), [&] (int x, int y) {return dfn[x] < dfn[y];} );
int nx = grace[i].size() - 1;
For (j, 1, nx) upd(grace[i][j - 1], grace[i][j], i);
}
For (i, 1, Node) if (!df[i]) tarjan(i);
For (u, 1, k) si[col[u]]++;
For (u, 1, Node)
for (auto v : G[u]) if (col[v] != col[u]) du[col[u]]++;
int Ans = 0x3f3f3f3f;
For (i, 1, k) if (!du[col[i]]) ckmin(Ans, si[col[i]] - 1);
cout << Ans;
return 0;
}
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