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template<class Node>
struct PersidentSegmentTree {
#define lc(u) tr[u].l
#define rc(u) tr[u].r
#define val(u) tr[u].v
    const int n;
    int tot = 0;
    vector<Node> tr;
    vector<int> root;

    PersidentSegmentTree(): n(0) {}

    PersidentSegmentTree(int n_): n(n_) {
        int N = (n << 5) + 10;
        tr.reserve(N); root.reserve(N);
        tr.resize(N); root.resize(N);
    }

    PersidentSegmentTree(vector<int>& a): PersidentSegmentTree(a.size() - 1) {
        function<void(int&, int, int)> build = [&](int& now, int l, int r) {
            now = ++ tot;
            if (l == r) {
                val(now) = a[l];
                return ;
            }
            int m = (l + r) >> 1;
            build(lc(now), l, m);
            build(rc(now), m + 1, r);
        };
        build(root[0], 1, n);
    }

    //last代表前缀，now代表新树根
    void insert(int& now, int last, int l, int r, int pos, int w) {
        now = ++ tot;
        tr[now] = tr[last];
        if (l == r) {
            val(now) = w;
            return;
        }
        int m = l + r >> 1;
        if (pos <= m)
            insert(lc(now), lc(last), l, m, pos, w);
        else
            insert(rc(now), rc(last), m + 1, r, pos, w);
    }

    //单点
    int query(int now, int l, int r, int pos) {
        if (l == r) {
            return val(now);
        }

        int m = l + r >> 1;
        if (pos <= m)
            return query(lc(now), l, m, pos);
        else
            return query(rc(now), m + 1, r, pos);
    }

    //区间查询 [u,v]->[root[l-1],root[r]]
    int query(int u, int v, int l, int r, int pos) {
        if (l == r) {
            return val(v);
        }

        int m = l + r >> 1;
        if (pos <= m)
            return query(lc(u), lc(v), l, m, pos);
        else
            return query(rc(u), rc(v), m + 1, r, pos);
    }
};

struct Node {
    int l, r, v;
};