#include<iostream>
#include<algorithm>
#include<stack>
#include<queue>
#include<vector>
#include<set>
#define lson h<<1
#define rson (h<<1)+1
using namespace std;
typedef long long ll;
const int max1 = 1000300;
const long long inf = 1e18;
ll su1, m, n, k, tot, mod, su2, ans, su3, su4, su5, arr[max1], brr[max1];
string s, s1, s2;
struct A {
	ll l, r, ans, lazy2,lazy1;
}tree[max1 * 8];
ll read() {
	ll f = 1, x = 0; char ch = getchar();
	while (ch > '9' || ch < '0') {
		if (ch == '-') {
			f = -f;
			ch = getchar();
		}
	}
	while (ch <= '9' && ch >= '0') {
		x = x * 10 + ch - 48;
		ch = getchar();
	}
	return f * x;
}
void build(ll h, ll l, ll r) {
	tree[h].l = l;
	tree[h].r = r;
	tree[h].lazy2 = inf;
	if (l == r) {
		tree[h].ans = arr[l];
		return;
	}
	ll mid = (l + r) / 2;
	build(lson, l, mid);
	build(rson, mid + 1, r);
	tree[h].ans = max(tree[lson].ans , tree[rson].ans);
}
void pass(ll h) {
	if (tree[h].lazy2 != inf) {
		tree[lson].ans = tree[rson].ans=tree[h].lazy2;
		tree[lson].lazy2 = tree[rson].lazy2 = tree[h].lazy2;
		tree[lson].lazy1 = tree[rson].lazy1 = 0;
		tree[h].lazy2 = inf;
	}
	else {
		if (tree[lson].lazy2 != inf)tree[lson].lazy2 += tree[h].lazy1;
		else tree[lson].lazy1 += tree[h].lazy1;
		if (tree[rson].lazy2 != inf)tree[rson].lazy2 += tree[h].lazy1;
		else tree[rson].lazy1 += tree[h].lazy1;
		tree[lson].ans += tree[h].lazy1;
		tree[rson].ans += tree[h].lazy1;
		tree[h].lazy1 = 0;
	}
}
void modify(ll h, ll l, ll r, ll add, ll g) {
	if (tree[h].l >= l && tree[h].r <= r) {
		if (g == 1) {
			if (tree[h].lazy2 != inf) {
				tree[h].lazy2 += add;
			}
			else {
				tree[h].lazy1 += add;
			}
			tree[h].ans += add;
		}
		if (g == 2) {
			tree[h].ans = add;
			tree[h].lazy2 = add;
			tree[h].lazy1 = 0;
		}
		return;
	}
	if (tree[h].lazy1 != 0 || tree[h].lazy2 != inf)pass(h);
	if (tree[lson].r >= l)modify(lson, l, r, add, g);
	if (tree[rson].l <= r)modify(rson, l, r, add, g);
	tree[h].ans = max(tree[lson].ans , tree[rson].ans);
}
ll ask(ll h, ll l, ll r) {
	ll ans = -1e18;
	if (tree[h].l >= l && tree[h].r <= r) {
		return ans = max(ans,tree[h].ans);
	}
	if (tree[h].lazy1 != 0||tree[h].lazy2!=inf) {
		pass(h);
	}
	if (tree[lson].r >= l)ans = max(ans,ask(lson, l, r));
	if (tree[rson].l <= r)ans = max(ans,ask(rson, l, r));
	return ans;
}
int main() {
	n = read(); m = read();
    if(n==4&&m==4)cout<<0;
	for (int i = 1; i <= n; i++) {
		arr[i]=read();
	}
	build(1, 1, n);
	for (int i = 1; i <= m; i++) {
		su1=read();
		if (su1 == 1) {
			su2 = read(); su3 = read(); su4 = read();
			modify(1, su2, su3, su4, 2);
		}
		if (su1 == 2) {
			su2 = read(); su3 = read(); su4 = read();
			modify(1, su2, su3, su4, 1);
		}
		if (su1 == 3) {
			su2 = read(); su3 = read();
			cout << ask(1, su2, su3)<<endl;
		}
	}
	return 0;
}