#include <bits/stdc++.h>
#define LL long long
#define QWQ -1145141919810
using namespace std;
LL n, q;
struct Tree
{
	int left, right;
	LL max;
	LL coverDelta;
	LL addDelta;
};
Tree tree[4 * 5000000 + 10];
LL a[500010];
#define ls id<<1
#define rs id<<1|1
void build(LL id, LL l, LL r)
{
	tree[id].left = l;
	tree[id].right = r;
	// tree[id].max = LLONG_MIN;
	if (l == r)
	{
		tree[id].coverDelta = QWQ;
		tree[id].max = a[l];
		return;
	}
	int mid = (l + r) / 2;
	build(id * 2, l, mid);
	build(id * 2 + 1, mid + 1, r);

	tree[id].max = max(tree[id * 2].max, tree[id * 2 + 1].max);

}
inline void coverpushdown(LL id)
{
	if (tree[id].coverDelta != QWQ)
	{
		tree[ls].addDelta = tree[rs].addDelta = 0;
		tree[ls].max = tree[rs].max = tree[id].coverDelta;
		tree[ls].coverDelta = tree[rs].coverDelta = tree[id].coverDelta;
		tree[id].coverDelta = QWQ;
	}
}
inline void addpushdown(LL id)
{
	if (tree[id].addDelta)
	{
		coverpushdown(id);
		tree[ls].max += tree[id].addDelta;
		tree[rs].max += tree[id].addDelta;
		tree[ls].addDelta +=tree[id].addDelta;
		tree[rs].addDelta += tree[id].addDelta;
		tree[id].addDelta = 0;
	}
}

inline void pushdown(LL id)
{
	coverpushdown(id);
	addpushdown(id);
}
inline void change(LL id, LL l, LL r, LL val)
{
	if (tree[id].left > r || tree[id].right < l)
		return;
	if (tree[id].left >= l && tree[id].right <= r)
	{
		tree[id].addDelta = 0;
		tree[id].max = val;
		tree[id].coverDelta = val;
		return;
	}
	pushdown(id);
	change(ls, l, r, val);
	change(rs, l, r, val);
	tree[id].max = max(tree[ls].max, tree[rs].max);
}

inline void update(LL id, LL l, LL r, LL delta)
{
	if (tree[id].left > r || tree[id].right < l)
		return;
	//	if (tree[id].left == tree[id].right)
	//		tree[id].max += delta;
	if (tree[id].left >= l && tree[id].right <= r)
	{
		coverpushdown(id);
		tree[id].max += delta;
		tree[id].addDelta += delta;
		return;
	}
	pushdown(id);

	update(2 * id, l, r, delta);
	update(2 * id + 1, l, r, delta);
	tree[id].max = max(tree[ls].max, tree[rs].max);
}

inline LL query(LL id, LL l, LL r)
{
	if (tree[id].left > r || tree[id].right < l)
		return LLONG_MIN;
	if (tree[id].left >= l && tree[id].right <= r)
	{
		return tree[id].max;
	}
	pushdown(id);
	
		return max(query(2 * id, l, r), query(2 * id + 1, l, r));
}
/*
void print_tree(int id)
{
	if (tree[id].left == tree[id].right)
	{
		printf("id = %lld, max = %lld, tree[id].left = %lld, tree[id].right = %lld \n", id, tree[id].max, tree[id].left, tree[id].right);
		//		cout << tree[id].max << " ";
		return;
	}
	printf("id = %lld, max = %lld, tree[id].left = %lld, tree[id].right = %lld \n", id, tree[id].max, tree[id].left, tree[id].right);
	print_tree(id * 2);
	print_tree(id * 2 + 1);
}*/

int main()
{
	ios::sync_with_stdio(false);
	// cin.tie(nullptr);
	cin >> n >> q;
	for (int i = 1; i <= n; i++)
		cin >> a[i];

	build(1, 1, n);
	//	print_tree(1);
	for (int i = 1; i <= n * 4+100; i++)
		tree[i].coverDelta = QWQ;

	LL op, x, l, r;
	while (q--)
	{
		cin >> op;
		if (op == 1)
		{
			cin >> l >> r >> x;
			change(1, l, r, x);
			//			print_tree(1);cout << endl;
		}
		else if (op == 2)
		{
			cin >> l >> r >> x;
			update(1, l, r, x);
			//			print_tree(1);cout << endl;
		}
		else
		{
			cin >> l >> r;
			cout << query(1, l, r) << endl;
		}
	}
	return 0;
}