#include<bits/stdc++.h>
typedef long long LL;
using namespace std;
const int MAXL = 2000005;
const LL INF = 1e18 + 5;
int N, Q;
struct segment_tree
{
	int lson, rson;
	long long dat, add, setting;
	bool set_;
};
segment_tree tree[MAXL];
LL num[MAXL];
int tail = 1, root = 1;
void maintain(int now, int l, int r)
{
	//printf("next:%d %d %d %lld\n", now, l, r, tree[now].dat);
	if(tree[now].set_)
	{
		//printf("set:%d %d %d %lld\n", now, l, r, tree[now].setting);
		if(tree[now].lson) 
		{
			tree[tree[now].lson].set_ = true;
			tree[tree[now].lson].setting = tree[now].setting;
			tree[tree[now].lson].dat = tree[now].setting;
		}
		if(tree[now].rson)
		{
			tree[tree[now].rson].set_ = true;
			tree[tree[now].rson].setting = tree[now].setting;
			tree[tree[now].rson].dat = tree[now].setting;
		}
	}
	else if(tree[now].add)
	{
		if(tree[now].lson) 
		{
			tree[tree[now].lson].add += tree[now].add;
			tree[tree[now].lson].dat += tree[now].add;
		}
		if(tree[now].rson) 
		{
			tree[tree[now].rson].add += tree[now].add;
			tree[tree[now].rson].dat += tree[now].add;
		}
	}
	//printf("next:%d %d %d %lld\n", now, l, r, tree[now].dat);
	tree[now].add = tree[now].setting = 0;
	tree[now].set_ = false;
}
void add(int now, int l, int r, int L, int R, LL vis)
{
	int mid = (l + r) >> 1;
	if(L <= l && r <= R) {
		//printf("now:%d %d %d %lld\n", now, l, r, tree[now].dat);
		tree[now].add += vis;
		tree[now].dat += vis;
		//printf("now:%d %d %d %lld\n", now, l, r, tree[now].dat);
		return;
	}
	maintain(now, l, r);
	if(L <= mid) add(tree[now].lson, l, mid, L, R, vis);
	if(R > mid) add(tree[now].rson, mid + 1, r, L, R, vis);
	if(r > l) tree[now].dat = max(tree[tree[now].lson].dat, tree[tree[now].rson].dat);
	return;
}
void set_vis(int now, int l, int r, int L, int R, LL vis)
{
	int mid = (l + r) >> 1;
	//maintain(now, l, r);
	if(L <= l && r <= R) {
		tree[now].set_ = true;
		tree[now].add = 0;
		tree[now].setting = vis;
		tree[now].dat = vis;
		return;
	}
	maintain(now, l, r);
	if(L <= mid) set_vis(tree[now].lson, l, mid, L, R, vis);
	if(R > mid) set_vis(tree[now].rson, mid + 1, r, L, R, vis);
	if(r > l) tree[now].dat = max(tree[tree[now].lson].dat, tree[tree[now].rson].dat);
}
LL query(int now, int l, int r, int L, int R)
{
	int mid = (l + r) >> 1;
	LL max_ = -INF;
	maintain(now, l, r);
	if(L <= l && r <= R) {
		return tree[now].dat;
	}
	maintain(now, l, r);
	if(L <= mid) max_ = max(query(tree[now].lson, l, mid, L, R), max_);
	if(R > mid) max_ = max(query(tree[now].rson, mid + 1, r, L, R), max_);
	return max_; 
}
void bulid(int now, int l, int r)
{
	if(l == r) {
		tree[now].dat = num[l];
		return;
	}
	int mid = (l + r) >> 1;
	if(!tree[now].lson) {
		tree[now].lson = ++tail;
	}
	bulid(tree[now].lson, l, mid);
	if(!tree[now].rson) {
		tree[now].rson = ++tail;
	}
	bulid(tree[now].rson, mid + 1, r);
	if(r > l) tree[now].dat = max(tree[tree[now].lson].dat, tree[tree[now].rson].dat);
	return;
}
void output(int now, int l, int r)
{
	printf("test: %d %d %d %lld %lld %lld\n", now, l, r, tree[now].dat, tree[now].setting, tree[now].add);
	if(l == r) return;
	int mid = (l + r) >> 1;
	output(tree[now].lson, l, mid);
	output(tree[now].rson, mid + 1, r);
	return;
}
inline void read()
{
	scanf("%d %d", &N, &Q);
	for(int i = 1; i <= N; i++)
		scanf("%lld", &num[i]);
	bulid(root, 1, N);
	//output(root, 1, N);
	return;
}
int main()
{
	//freopen("test.txt","r",stdin);
	//freopen("output.txt","w",stdout);
	tree[0].dat = -INF;
	read();
	for(int i = 0; i < Q; i++)
	{
		int op;
		scanf("%d", &op);
		if(op == 1) {
			int l, r;
			LL vis;
			scanf("%d %d %lld", &l, &r, &vis);
			set_vis(root, 1, N, l, r, vis);
			//output(root, 1, N);
		}
		else if(op == 2) {
			int l, r;
			LL vis;
			scanf("%d %d %lld", &l, &r, &vis);
			add(root, 1, N, l, r, vis);
			//output(root, 1, N);
		}
		else if(op == 3) {
			int l, r;
			scanf("%d %d", &l, &r);
			printf("%lld\n", query(root, 1, N, l, r));
		}
	}
	return 0;
}
/*
10 10
1 4 2 5 3 2 2 1 -9 3

*/