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| #include <queue>
#include <cstdio>
#include <algorithm>
using namespace std;
const int maxn = 100005;
bool vis[maxn], col[maxn];
pair<int, int> res;
struct edge_t { int to, next; } edge[maxn << 1];
int n, m, N, siz[maxn], h[maxn], cnte, fa[maxn], dep[maxn], clo, id[maxn], mi[maxn << 1][20], cnt_black, L2[maxn << 1];
inline int getint() {
int r = 0; bool z = true; char c = getchar();
for (; c < '0' || c > '9'; c = getchar()) if (c == '-') z = false;
for (; '0' <= c && c <= '9'; c = getchar()) r = r * 10 - '0' + c;
if (z) return r;
return -r;
}
inline void ins(int x, int y) {
edge[++cnte].to = y;
edge[cnte].next = h[x];
h[x] = cnte;
}
struct ly {
priority_queue<int> a, b;
inline void nn() { while (b.size() && a.top() == b.top()) a.pop(), b.pop(); }
inline int siz() { return a.size() - b.size(); }
inline int fir() { nn(); return a.top(); }
inline void del(int x) { b.push(x); nn(); }
inline void add(int x) { nn(); a.push(x); }
inline int sec() {
int mag = fir(); a.pop();
int hsk = fir(); add(mag);
return mag + hsk;
}
} h1[maxn], h2[maxn], ans;
void fetch(int now, int father, int deep, ly& dst) {
siz[now] = 1; dst.add(deep);
for (int i = h[now]; i; i = edge[i].next) {
if (vis[edge[i].to] || father == edge[i].to) continue;
fetch(edge[i].to, now, deep + 1, dst);
siz[now] += siz[edge[i].to];
}
}
void dfs(int now, int father, int deep) {
dep[now] = mi[++clo][0] = deep; id[now] = clo;
for (int i = h[now]; i; i = edge[i].next) {
if (edge[i].to == father) continue;
dfs(edge[i].to, now, deep + 1);
mi[++clo][0] = deep;
}
}
inline void add(ly& x) { if (x.siz() > 1) ans.add(x.sec()); }
inline void del(ly& x) { if (x.siz() > 1) ans.del(x.sec()); }
inline int lyn(int a, int b) {
a = id[a]; b = id[b];
if (a > b) swap(a, b);
int t = L2[b-a+1];
return min(mi[a][t], mi[b-(1<<t)+1][t]);
}
inline int calc(int x, int y) { return dep[x] + dep[y] - (lyn(x, y) << 1); }
inline void modify(int x) {
bool sta = !col[x];
if (sta) ++cnt_black; else --cnt_black;
del(h2[x]);
if (sta) h2[x].add(0); else h2[x].del(0);
add(h2[x]);
for (int i = x; fa[i]; i = fa[i]) {
del(h2[fa[i]]);
if (h1[i].siz() > 0) h2[fa[i]].del(h1[i].fir());
if (sta) h1[i].add(calc(x, fa[i])); else h1[i].del(calc(x, fa[i]));
if (h1[i].siz() > 0) h2[fa[i]].add(h1[i].fir());
add(h2[fa[i]]);
}
col[x] = sta;
}
void find_root(int now, int father) {
int tmp = 1; siz[now] = 1;
for (int i = h[now]; i; i = edge[i].next) {
if (vis[edge[i].to] || father == edge[i].to) continue;
find_root(edge[i].to, now);
siz[now] += siz[edge[i].to];
tmp = max(tmp, siz[edge[i].to]);
}
tmp = max(tmp, N - siz[now]);
res = min(res, make_pair(tmp, now));
}
int get_root(int now, int father, int size) {
res = make_pair(2147483647, 0);
N = size;
find_root(now, father);
return res.second;
}
void solve(int now) {
int i, j;
h2[now].add(0);
vis[now] = true;
for (i = h[now]; i; i = edge[i].next) {
if (vis[edge[i].to]) continue;
ly tmp;
fetch(edge[i].to, now, 1, tmp);
j = get_root(edge[i].to, now, siz[edge[i].to]);
h1[j] = tmp; fa[j] = now;
h2[now].add(tmp.fir());
solve(j);
}
add(h2[now]);
}
int main() {
n = cnt_black = getint(); int x, y;
for (int i = 1; i < n; ++i) {
x = getint(); y = getint();
ins(x, y); ins(y, x);
col[i] = true;
}
col[n] = true; dfs(1, 0, 0);
for (int i = 2; i <= clo; ++i) L2[i] = L2[i>>1]+1;
for (int j = 1; j <= 19; ++j)
for (int i = 1; i + (1<<j) - 1 <= clo; ++i)
mi[i][j] = min(mi[i][j-1], mi[i+(1<<(j-1))][j-1]);
solve(get_root(1, 0, n));
char str[3];
int Q = getint();
while (Q--) {
scanf("%s", str);
if (str[0] == 'C') modify(getint());
else {
if (cnt_black < 2) printf("%d\n", cnt_black - 1);
else printf("%d\n", ans.fir());
}
}
}
|