const int N = 1e5 + 5;
vector<pair<int, int>> g[N];
int low[N], dfn[N], tot = 0;
pair<int, int> fa[N];
bool is_cut[N], is_bridge[N];
void tarjan(int u, pair<int, int> o) {fa[u] = o;dfn[u] = low[u] = ++tot;for (pair<int, int> p : g[u]) {int v = p.fi;if(!dfn[v]) {tarjan(v, {u, p.se});low[u] = min(low[u], low[v]);}else if(v != o.fi) low[u] = min(low[u], dfn[v]);}
}
void solve(int n) {tarjan(1, {1, 1});//求割点int son = 0;for (int v = 2; v <= n; v++) {if(fa[v].fi == 1) son++;else {int u = fa[v].fi;if(low[v] >= dfn[u]) is_cut[u] = true;}}if(son >= 2) is_cut[1] = true;//求桥for (int v = 2; v <= n; v++) {int u = fa[v].fi;if(low[v] > dfn[u]) is_bridge[fa[v].se] = true;}
}

const int N = 1e5 + 5;
vector<int> g[N];
vector<int> bcc[N];
bool vis[N];
int low[N], dfn[N], stk[N], tot = 0, top = 0, cnt = 0;
void tarjan(int u, int fa) {low[u] = dfn[u] = ++tot;stk[++top] = u;vis[u] = true;for (int v : g[u]) {if(v == fa) continue;if(!dfn[v]) {tarjan(v, u);low[u] = min(low[u], low[v]);}else if(vis[v]) low[u] = min(low[u], dfn[v]);}if(low[u] == dfn[u]) {++cnt;while(stk[top] != u) vis[stk[top]] = false, bcc[cnt].pb(stk[top--]);vis[stk[top]] = false, bcc[cnt].pb(stk[top--]);}
}

const int N = 1e5 + 5;
vector<int> g[N];
vector<pair<int,int>> bcc[N];
int low[N], dfn[N], tot = 0, top = 0, cnt = 0;
pair<int,int> stk[N];
void tarjan(int u, int fa) {low[u] = dfn[u] = ++tot;for (int v : g[u]) {pair<int,int> e = {u, v};if(!dfn[v]) {stk[++top] = e;tarjan(v, u);low[u] = min(low[u], low[v]);if(low[v] >= dfn[u]) {cnt++;while(stk[top] != e) {bcc[cnt].push_back(stk[top--]);}bcc[cnt].push_back(stk[top--]);}}else if(v != fa ) {if(dfn[v] < dfn[u]) stk[++top] = e, low[u] = min(low[u], dfn[v]);}}
}