为什么编译出错？QAQ

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 1e5+7;
int v[N * 2], n, mod, p, root, cnt;

struct node {
	int lson, rson, add, mul, sum;
} a[N * 2];

void build (int &k, int l, int r) {
	k = ++ cnt;
	a[k].mul = 1;
	if (l == r) a[k].sum = v[l] % mod;
	else {
		int mid = (l + r) / 2;
		build(a[k].lson, l, mid);
		build(a[k].rson, mid + 1, r);
		a[k].sum = (a[a[k].lson].sum + a[a[k].rson].sum) % mod;
	}
}

inline void addtag(int k, int l, int r, int add, int mul) {
	a[k].sum = (a[k].sum * mul + (r - l + 1) * add) % mod;
	a[k].add = (a[k].add * mul + add) % mod;
	a[k].mul = (a[k].mul * mul) % mod;
}

void modify(int k, int l, int r, int ql, int qr, int add, int mul) {
	if (l == ql && r == qr) {
		addtag(k, l, r, add, mul);
	} else {
		int mid = (l + r) / 2;
		addtag(a[k].lson, l, mid, a[k].add, a[k].mul);
		addtag(a[k].rson, mid + 1, r, a[k].add, a[k].mul);
		a[k].add = 0; a[k].mul = 1;
		if (qr <= mid) modify(a[k].lson, l, mid, ql, qr, add, mul);
		else if (ql > mid) modify(a[k].lson, l, mid, ql, qr, add, mul);
		else {
			modify(a[k].lson, l, mid, ql, mid, add, mul);
			modify(a[k].rson, mid + 1, r, mid + 1, qr, add, mul);
		}
		a[k].sum = (a[a[k].lson].sum + a[a[k].rson].sum) % mod;
	}
}

int query(int k, int l, int r, int ql, int qr, int add, int mul) { //把mudify复制一遍，稍微改改 
	if (l == ql && r == qr) {
		return (a[k].sum) % mod;
	} else {
		int mid = (l + r) / 2;
		addtag(a[k].lson, l, mid, a[k].add, a[k].mul);
		addtag(a[k].rson, mid + 1, r, a[k].add, a[k].mul);
		a[k].add = 0; a[k].mul = 1;
		if (qr <= mid) return query(a[k].lson, l, mid, ql, qr, add, mul);
		else if (ql > mid) return query(a[k].lson, l, mid, ql, qr, add, mul);
		else {
			int k1 = query(a[k].lson, l, mid, ql, mid, add, mul)
			int k2 = query(a[k].rson, mid + 1, r, mid + 1, qr, add, mul);
			return (k1 + k2) % mod;
		}
		//a[k].sum = (a[a[k].lson].sum + a[a[k].rson].sum) % mod;
	}
}

signed main() {
	cin.tie(0); ios::sync_with_stdio(0);
	cin >> n >> p >> m;
	for (int i = 1; i <= n; i++) cin >> v[i];
	build(root, 1, n);
	for (int i = 1; i <= p; i++) {
		int op, x, y, k;
		cin >> op;
		if (op == 1) {
			cin >> x >> y >> k;
			modify(root, 1, n, x, y, 0, k);
		} else if (op == 2) {
			cin >> x >> y >> k;
			modify(root, 1, n, x, y, k, 1);
		} else {
			cin >> x >> y;
			cout << query(root, 1, n, x, y) << "\n";
		}
	}
	return 0;
}