#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define lid (id << 1)
#define rid (id << 1 | 1)
#define none -2147483647
struct node{
	int l, r;
	ll maxx, lazy, lazy2;
}tr[4000005];
int n, m, op, l, r, k, a[1000005];
void pushup(int id){
	tr[id].maxx = max(tr[lid].maxx, tr[rid].maxx);
}
void pushdown(int id){
	if (tr[id].l == tr[id].r) return;
	if (tr[id].lazy2 != none){
		tr[lid].lazy2 = tr[id].lazy2;
		tr[rid].lazy2 = tr[id].lazy2;
		tr[lid].maxx = tr[id].lazy2;
		tr[rid].maxx = tr[id].lazy2;
		tr[id].lazy2 = none;
	}
	else if (tr[id].lazy){
		tr[lid].lazy += tr[id].lazy;
		tr[rid].lazy += tr[id].lazy;
		tr[lid].maxx += tr[id].lazy;
		tr[rid].maxx += tr[id].lazy;
		tr[id].lazy = 0;
	}
}
void build(int id, int l, int r){
	tr[id].l = l;
	tr[id].r = r;
	tr[id].lazy = 0;
	tr[id].lazy2 = none;
	if (l == r){
		tr[id].maxx = a[l];
		return;
	}
	int mid = (l + r) >> 1;
	build(lid, l, mid);
	build(rid, mid + 1, r);
	pushup(id);
}
void add(int id, int l, int r, int x){
	pushdown(id);
	if (l <= tr[id].l && tr[id].r <= r){
		tr[id].maxx += x;
		if (tr[id].lazy2 != none) tr[id].lazy2 += x;
		else tr[id].lazy += x;
		return;
	}
	int mid = (tr[id].l + tr[id].r) / 2;
	if (r <= mid) add(lid, l, r, x);
	else if (l > mid) add(rid, l, r, x);
	else add(lid, l, mid, x), add(rid, mid + 1, r, x);
	pushup(id);
}
void modify(int id, int l, int r, int x){
	pushdown(id);
	if (l <= tr[id].l && tr[id].r <= r){
		tr[id].maxx = x;
		tr[id].lazy2 = x;
		tr[id].lazy = 0;
		return;
	}
	int mid = (tr[id].l + tr[id].r) >> 1;
	if (r <= mid) modify(lid, l, r, x);
	else if (l > mid) modify(rid, l, r, x);
	else modify(lid, l, mid, x), modify(rid, mid + 1, r, x);
	pushup(id);
}
ll query(int id, int l, int r){
	pushdown(id);
	if (l <= tr[id].l && tr[id].r <= r) return tr[id].maxx;
	int mid = (tr[id].l + tr[id].r) / 2;
	if (r <= mid) return query(lid, l, r);
	if (l > mid) return query(rid, l, r);
	return max(query(lid, l, mid), query(rid, mid + 1, r));
}
void print_seg(){
	for (int i = 1;i <= n;i++) cout << query(1, i, i) << ' ';
	cout << '\n';
}
int main(){
	//ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cin >> n >> m;
	for (int i = 1;i <= n;i++){
		cin >> a[i];
	}
	build(1, 1, n);
	//print_seg();
	while(m--){
		cin >> op >> l >> r;
		if (op == 1){
			cin >> k;
			modify(1, l, r, k);
		}
		else if (op == 2){
			cin >> k;
			add(1, l, r, k);
		}
		else{
			cout << query(1, l, r) << '\n';
		}
		//print_seg();
	}
	return 0;
}