#include <bits/stdc++.h>
using namespace std; 

#define int long long

const int N = 1e6 + 5, INF = 1e18; 

struct Tree {
	int val, lazy_add, lazy_change; 
} tree[N<<3]; 

int a[N]; 

void push_up (int rt) {
	tree[rt].val = max(tree[rt<<1].val, tree[rt<<1|1].val); 
}

void push_down_change (int rt, int l, int r) {
	if (tree[rt].lazy_change != -INF) {
		int lazy = tree[rt].lazy_change, ls = rt << 1, rs = ls | 1; 
		tree[ls].lazy_add = tree[rs].lazy_add = 0; 
		tree[ls].lazy_change = lazy; 
		tree[rs].lazy_change = lazy; 
		tree[ls].val = lazy; 
		tree[rs].val = lazy; 
		tree[rt].lazy_change = -INF; 
	}
}

void push_down_add (int rt, int l, int r) {
	if (tree[rt].lazy_add) {
		push_down_change(rt, l, r); 
		int lazy = tree[rt].lazy_add, ls = rt << 1, rs = ls | 1; 
		tree[ls].lazy_add += lazy; 
		tree[rs].lazy_add += lazy; 
		tree[ls].val += lazy; 
		tree[rs].val += lazy; 
		tree[rt].lazy_add = 0; 
	}
}

void push_down (int rt, int l, int r) {
	push_down_change(rt, l, r); 
	push_down_add(rt, l, r); 
}

void build (int rt, int l, int r) {
	if (l == r) {
		tree[rt].val = a[l]; 
		tree[rt].lazy_add = 0; 
		tree[rt].lazy_change = -INF; 
		return; 
	}
	int mid = (l + r) >> 1; 
	build(rt << 1, l, mid); 
	build(rt << 1 | 1, mid + 1, r); 
	push_up(rt); 
}

void update (int rt, int l, int r, int ql, int qr, int num, int op) {
	if (l > qr || r < ql) return; 
	if (l >= ql && r <= qr) {
		if (op == 1) {
			tree[rt].lazy_add = 0; 
			tree[rt].val = num; 
			tree[rt].lazy_change = num; 
		} else if (op == 2) {
			push_down_change(rt, l, r); 
			tree[rt].val += num; 
			tree[rt].lazy_add += num; 
		}
		return; 
	}
	push_down(rt, l, r); 
	int mid = (l + r) >> 1; 
	update(rt << 1, l, mid, ql, qr, num, op); 
	update(rt << 1 | 1, mid + 1, r, ql, qr, num, op); 
	push_up(rt); 
}

int query (int rt, int l, int r, int ql, int qr) {
	if (r < ql || qr < l) return -INF; 
	if (ql <= l && r <= qr) return tree[rt].val; 
	push_down(rt, l, r); 
	int mid = (l + r) >> 1; 
	return max(query(rt << 1, l, mid, ql, qr), query(rt << 1 | 1, mid + 1, r, ql, qr)); 
}

signed main () {
	
	ios::sync_with_stdio(0); 
	cin.tie(0), cout.tie(0); 
	
	int n, q, op, x, y, z; 
	cin >> n >> q; 
	for (int i = 1; i <= n; i++) cin >> a[i]; 
	build(1, 1, n); 
	while (q--) {
		cin >> op >> x >> y; 
		if (op == 1 || op == 2) cin >> z, update(1, 1, n, x, y, z, op); 
		else cout << query(1, 1, n, x, y) << endl; 
	}
	return 0; 
}