#include<bits/stdc++.h>
using namespace std;
#define ll long long
const int N = 1e6 + 7;
const ll inf = 1e18 + 7;
ll num[N];
struct segment_tree
{
	struct node
	{
		int l, r;//开始位置，结束位置
		ll add, pre;
		ll change;
		bool used;
	}tr[N << 2];
	inline void pushup(int p)//条件修改
	{
		tr[p].pre = max(tr[p << 1].pre, tr[p << 1 | 1].pre);
	}
	inline void build(int p,int l, int r)
	{
		tr[p] = { l,r,0,-inf,0,false };
		if (l == r)
		{
			tr[p].pre = num[l];
			return;
		}
		int mid = (l + r) >> 1;
		build(p << 1, l, mid);
		build(p << 1 | 1, mid + 1, r);
		pushup(p);
	}
	inline void spread(int p)
	{
		if (tr[p].used)
		{
			tr[p << 1].pre = tr[p].change;
			tr[p << 1 | 1].pre = tr[p].change;
			tr[p << 1].change = tr[p].change;
			tr[p << 1 | 1].change = tr[p].change;
			tr[p << 1].used = true;
			tr[p << 1 | 1].used = true;
			tr[p << 1].add = 0;
			tr[p << 1 | 1].add = 0;
		}
		else if (tr[p].pre)
		{
			tr[p << 1].pre += tr[p].add;
			tr[p << 1].add += tr[p].add;
			tr[p << 1 | 1].pre += tr[p].add;
			tr[p << 1 | 1].add += tr[p].add;
			tr[p].add = 0;
		}
		tr[p].add = 0;
		tr[p].used = false;
	}
	inline void change(int p, int l, int r, ll k)//区间修改
	{
		if (tr[p].l >= l && tr[p].r <= r)
		{
			tr[p].pre = k;
			tr[p].used = true;
			tr[p].add = 0;
			tr[p].change = k;
			return;
		}
		spread(p);
		int mid = (tr[p].l + tr[p].r) >> 1;
		if (l <= mid) change(p << 1, l, r, k);
		if (r > mid) change(p << 1 | 1, l, r, k);
		pushup(p);
	}
	inline void modify(int p, int l, int r, ll k)//区间增加
	{
		if (tr[p].l >= l && tr[p].r <= r)
		{
			tr[p].pre += k;
			tr[p].add += k;
			return;
		}
		spread(p);
		int mid = (tr[p].l + tr[p].r) >> 1;
		if (l <= mid) modify(p << 1, l, r, k);
		if (r > mid) modify(p << 1 | 1, l, r, k);
		pushup(p);
	}
	inline ll query(int p, int l, int r)//区间求最大值
	{
		ll ans = -inf;
		if (tr[p].l >= l && tr[p].r <= r)
			return tr[p].pre;
		spread(p);
		int mid = (tr[p].l + tr[p].r) >> 1;
		if (l <= mid) ans = max(ans, query(p << 1, l, r));
		if (r > mid) ans = max(ans, query(p << 1 | 1, l, r));
		return ans;
	}
}ST;
int main()
{
	int n, q;
	cin >> n >> q;
	for (int i = 1; i <= n; i++)
		cin >> num[i];
	ST.build(1, 1, n);
	while (q--)
	{
		int op, l, r, x;
		cin >> op;
		if (op == 1)
		{
			cin >> l >> r >> x;
			ST.change(1, l, r, x);
		}
		else if (op == 2)
		{
			cin >> l >> r >> x;
			ST.modify(1, l, r, x);
		}
		else
		{
			cin >> l >> r;
			cout << ST.query(1, l, r) << endl;
		}
	}
	return 0;
}

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