#include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
using namespace std;
#define ll long long
#define lll __int128
#define ull unsigned long long
#define veci vector<int>
#define vecl vector<long long>
const int N = 1e6 + 10, inf = 0x7FFFFFFF;
const ll INF = 0x7FFFFFFFFFFFFFFF;
template<typename T>inline void readT(T& x) {
	bool f = 1; x = 0; char ch = getchar();
	while (ch < '0' || ch>'9') { if (ch == '-') f = !f; ch = getchar(); }
	while (ch >= '0' && ch <= '9') { x = (x << 1) + (x << 3) + (ch ^ 48); ch = getchar(); }
	x = (f ? x : -x); return;
}
template<typename T>
inline void writeT(T x) {
	if (x < 0) putchar('-'), x = -x;
	if (x > 9) writeT(x / 10);
	putchar(x % 10 + '0'); return;
}
struct tree {
	vecl t, vis1, vis2, e, ls, rs;//1赋值，2加法
	ll tot = 0, len, begin = 0;
	ll build(ll& x, ll l, ll r) {
		if (!x)x = ++tot;
		//		cout<<x<<" "<<l<<" "<<r<<'\n';
		if (l == r)
			return t[x] = e[l - 1];
		ll mid = (l + r) >> 1;
		return t[x] = max(build(ls[x], l, mid), build(rs[x], mid + 1, r));
	}
	tree(vecl a) {
		len = a.size();
		e = a;
		vecl num(2 * len);
		t = vis1 = vis2 = ls = rs = num;
		for (auto& n : vis1)
			n = INF;
		build(begin, 1, len);
	}
	void push_down(ll x) {
		if (vis1[x] != INF) {
			vis1[x] += vis2[x];
			t[x] = vis1[x];
			vis1[ls[x]] = vis1[x];
			vis1[rs[x]] = vis1[x];
			vis2[ls[x]] = 0;
			vis2[rs[x]] = 0;
			vis2[x] = 0;
			vis1[x] = INF;
		}
		else {
			t[x] += vis2[x];
			vis2[ls[x]] += vis2[x];
			vis2[rs[x]] += vis2[x];
			vis2[x] = 0;
		}
		return;
	}
	ll updata1(ll x, ll l, ll r, ll L, ll R, ll k) {
		push_down(x);
		if (L <= l && r <= R) {
			vis1[x] = k;
			push_down(x);
			return t[x];
		}
		ll mid = (l + r) >> 1, rt = -INF;
		if (mid >= L)rt = max(rt, updata1(ls[x], l, mid, L, R, k));
		else push_down(ls[x]), rt = max(rt, t[ls[x]]);
		if (mid < R)rt = max(rt, updata1(rs[x], mid + 1, r, L, R, k));
		else push_down(rs[x]), rt = max(rt, t[rs[x]]);
		return t[x] = rt;
	}
	ll updata2(ll x, ll l, ll r, ll L, ll R, ll k) {
		push_down(x);
		if (L <= l && r <= R) {
			vis2[x] = k;
			push_down(x);
			return t[x];
		}
		ll mid = (l + r) >> 1, rt = -INF;
		if (mid >= L)rt = max(rt, updata2(ls[x], l, mid, L, R, k));
		else push_down(ls[x]), rt = max(rt, t[ls[x]]);
		if (mid < R)rt = max(rt, updata2(rs[x], mid + 1, r, L, R, k));
		else push_down(rs[x]), rt = max(rt, t[rs[x]]);
		return t[x] = rt;
	}
	ll query(ll x, ll l, ll r, ll L, ll R) {
		push_down(x);
		if (L <= l && r <= R)
			return t[x];
		ll mid = (l + r) >> 1, rt = -INF;
		if (mid >= L)rt = max(rt, query(ls[x], l, mid, L, R));
		if (mid < R)rt = max(rt, query(rs[x], mid + 1, r, L, R));
		return rt;
	}
};
int main() {
	int n, q;
	readT(n); readT(q);
	vecl a(n);
	for (int i = 0; i < n; i++)
		readT(a[i]);
	tree tr(a);
	while (q--) {
		//		for(auto e:tr.t)
		//			cout<<e<<" ";
		//		cout<<'\n';
		int op;
		cin >> op;
		if (op == 1) {
			int l, r, x;
			cin >> l >> r >> x;
			tr.updata1(1, 1, n, l, r, x);
		}
		if (op == 2) {
			int l, r, x;
			cin >> l >> r >> x;
			tr.updata2(1, 1, n, l, r, x);
		}
		if (op == 3) {
			int l, r;
			cin >> l >> r;
			writeT(tr.query(1, 1, n, l, r));
			putchar('\n');
		}
	}
	return 0;
}